Let's start off with a note/warning first. I cannot within reason explain even minorly what my opinions/thoughts are on this masterpiece without "spoiling" it a little. Though I don't think it should be a problem, because when you are in school, and your teachers mention a great book in literature and it's events, you would still read it if you are interested and enjoy, despite knowing what may happen. If you are interested in SEL, and want (or watched) it, my review will incite you to seek more to this (or think, understand better). Now on to the actual (rather long) review:
Now you have heard this many times how Lain is unique and fantastic. And it is unique in terms of how much of a classic it truly is, and how it's the anime genres’ more philosophical/ cultic anime title. Sadly, many struggle to find meaning in the anime itself despite what it has to offer. Hence why I never recommend it to anyone. Though many surely begin their journey with SEL due to encountering countless Lainfags on the internet, which is an understandable standpoint!
People forget, or just don't know, that this is an anime made to make you think, and immerse you with ideas. "Serial Experiment" already states how this general idea is a serialized (PS1 game + Anime) social thought experiment for the viewer made to do their research upon. This anime is not for people who seek a fantastic journey and feelings in SEL, that they usually see in other, more popular anime. The creators of Lain have made a progressive cyberpunk anime which is HIGHLY informed and operative on multiple layers, both figuratively and literally. No single explanation or speech or essay can hope to encompass all that is Serial Experiments Lain, even this review will not cover 10-20% of what you can see. As such, Lain will always be open to interpretation and always encourage us to do our own research, our own experiments. If you don't like thinking outside the box, think of SEL more as an anime where a person struggles in three worlds of existence: on the internet, on the mental field, and in reality. However still tries to find meaning in her life, and of the world given her stimuli and experiences. Now your perception & receptivity makes Lain far more ideal to watch.
What I love most about SEL great music and classic opening aside, is that the anime's story can be interpreted in some ways. Though the main themes are definitely about existentialism, idealism and about the internet & cyber world in general. However Lain's character can be interpreted in two major ways. One being less detailable, the other is much more philosophical. (Here is where minor spoiler phobic people should close the review).
-Lain is a byproduct of the Protocol-7 (the project responsible for the merging of the Wired and the Real World) and she is created as a Jesus/God like figure that will save & lead Humanity in exchange for her very own life. This Lain of the Wired's activities quickly make the The Knights interested (the MIB you see stalking over Lain by the later episodes) as their goal might be to unite human consciousness with the "divine" "true" consciousness, which is through this ever-so-famous, prophetlike entity that is Lain starts to be. However Lain starts to get more understanding of her origin. Her fake dad, her fake friends. her fake life, the fake world, and fake struggle against what it means to be God, as seen by the latter episodes. She came to understand that she is not human in reality, and that if she erases everything, she is forever saved from the destiny she was made to.
-Or that she is just an average user who finds herself getting lost in this new world. After many time spent on said new world, her reality starts fading, and she'd have such strong delusions and philosophical wonders, which is why the anime can be really loved, and which I will be writing about later. She also develops DID, Dissociative Identity Disorder, that creates three sense of Lain further in the story, and the Wired just so happened to influence that.
Just, for a second imagine yourself as Lain shown in the second example for real. The Internet isn't really that common in the world, this completely new technology feels so... alien, yet so inviting, that you feel it was made for you. However the issue is, you hardly know much about it, nor computers for that matter. But eventually it drags you in. You see this insanely strange sense of being perceived, and connected to others. A whole new perception of the world just opens up in front of you. A COMPLETELY new world! It was said how Lain is insanely lonely before, and the fact how much she could connect to everyone by the power of the Wired, throughout the anime is insane. It made her realize that humans are indeed connected. But she questioned the ego around the people. What is their purpose? What purpose does she have herself as well...?
And she seeked more of this. She started to heavily invest all that is the wired, she started taking everything that could make her feel more "awake", even by integrating many things into her computer. Her idea of feeling more awake reached to the point of completely believing bodies are unnecessary, as these limitations hinders us in connection & growth, or hinders our ability to find meaning within our lives, as a lifespan is too little to "fill" that answer for us. As she dives deeper and deeper into this completely vast world, she finds out that she is having influence, and due to the fact how, just like you, can act so much differently with others online due to the power of anonymity, she begins to ask what even is she? Till it eventually worsens to a disorder level, and even when she hangs with her friends, she struggles in her head knowing she isn't herself anymore, this was one of the scenes shown in the anime.
Not only that, but in the current universe, the saying "everything is connected" means a far greater meaning. This is also the great quote said by the anime repeatedly "humans are connected on a subconscious level" . One could reasonably state that there is no moment when something isn't observed by a multitude of senses - be it those of living beings, or the clashing of molecules and waves with each other, creating a sort of 'universal sense' of existence. Even the Earth itself has a constant magnetic field, all atoms connected to each other, which we subconsciously perceive, and are connected to. The philosophy of idealism & existentialism truly starts to make a new understanding about how we perceive such things, because many things are connected, it always have been, we just don't think about it, so we don't see it as "existing". However it is there, as said in the anime by this exact example (during the documentary found in layer:09 "PROTOCOL")
Interestingly enough, if you go deep enough - down to sub-atomic particles, this vast 'universal sense' breaks down and ceases to be a constant. There are waves that only 'decide' what state they are in once directly observed. This is the phenomenon at the base of quantum physics.
This means that while at the macro-level, for example a tree will always make a sound, even if alone in the field. However, at the sub-atomic scale, deep down inside even atoms, there is a world perceived by other atoms where it may make both sound and no sound at all, at the same time.
Given this epiphany about the fundamental nature of the Universe, Lain may be ultimately both correct and incorrect at the same time regarding her sophos.
Of further interest, the ending speaks about one more new thing. That is whether or not one can ever truly 'erase' information at all. Given enough tertiary information, we should be able to trace back anything that ever happened in the Universe, given how everything is interconnected and the ripples of an action live on in perpetuity. Because information, and everything in this world crosses time and space as no more than motes of dust, light, and radiation, the only thing that might be able to destroy information is a black hole. And even then, it might only just convert it through complex, but not fundamentally unknowable processes. To put it simply, convert into something else we are yet to understand.
What I'm getting at is that while Lain could be both right and wrong regarding her views on existence, she is most likely fundamentally wrong regarding her ability to erase information. Even when your empty your trash can on your PC those deleted files aren't truly deleted. Because the best she could do, is mask it for those unable to look deeper. And just like someone or something capable of piecing back her existence from the ripples she left behind, we can see her, and her journey. We remember her. Thus, Lain is, ultimately, still alive, and will be "alive" as information in our minds, even if she doesn't realize this herself through her world.
That wraps up the anime in a nutshell, however it's worth noting that the PS1 Game gives a much greater sense of this "piecing back her existence" as we are to piece tons upon tons of files linked to her and her life, that honestly after a while was emotionally draining. If you wish to play the game, you needn't have an emulator, or a PS1 & Copy for it luckily. Just go and open https://laingame.net
There are even more philosophy things in there, and even stronger feels, and better relatability. Also the story there is about Lain and her therapist.
Thank you for reading, and I hope you enjoyed reading this massive text! It'd be awesome if it either incited you to watch it, re-watch it, or to think more about it. Or on the other hand, helped you understand it much better! :)