Being a huge fan of the OG S;G, I was pretty disappointed with this one. Over abundance of fan service moments ruined the experience for me, as well as the redesigns for some of the characters. The anime couldn't adapt the VN well because the VN wasn't linear as the original. A lot of forgotten sub-plots. Some memorable moments but it's muddled in there. There's also an abundance of useless filler characters instead of focusing on the main cast of the original. Wish I could call it a worthy successor but I can't.
SPOILER TERRITORY

• Kagari is without a doubt one of the worst additions in the series as a whole. Even from the way she's designed, it's clear they wanted to bait fans into thinking "Woah did Kurisu have a sister/daugher?" and turning it into a red herring. Adds unneeded conflict between the characters.
• A way to improve the story would've been to just focus on Suzuha, Okabe, Daru, and Mayuri. Their experiences of reading steiner with Kurisu should've motivated them to focus on getting Okabe back into his feet. The WWIII plotline is inevitable, but leave the Kagari stuff out. She was never mentioned in the OG S;G and there was no reason to use her as weeb bait.
• Another think I dislike are the new character designs, Mayuri drastically changed from her appearance in S;G, Daru now has straps and fingerless gloves. Okabe is the only one that I like, his attire is pretty good and reflective of how he is feeling. (Depressed = wearing black as if he was at a funeral, like Kurisu's.). The color tone of the series is also a downgrade from the original. It's shown as all bright and lively, especially most of the cast's attire, and it doesn't have that same blue atmospheric tint the original steins;gate had that made it more eye catching and somber.
• A bunch of subplots lead nowhere, for example the Yuki plotline which was fully developed in the S;G 0 visual novel, is hinted throughout the anime, where Yuki hurts her hand multiple times (where she was supposed to be one of Leskinen's minions) but is then never mentioned again and the subplot is completely dropped. I'm surprised that people have never commented on this because this was very jarring even during my first watch.
• Unlike the original steins;gate, which knew when to put in their fanservice moments, steins;gate 0 just has it all over the place. The tones change drastically when putting it where it doesn't need to be. The original had a bunch of shots here and there but never made it run that long. Most of its SOL moments were built up for the fallout after episode 12. Here it's just treated like a regular generic anime, and detracts the serious tone the show COULD'VE carried.

• What I do like is Suzuha and Daru's more developed relationship. He's less of a pervert now (but still is one) and contributes a lot more to the plot than he did in the original steins;gate, where he was just used as comic relief despite being Okabe's best male friend.
• I also like the small snippets when Okabe was in emotional turmoil. Really showed how heartbreaking his situation was. Also the contrasting attitude is perfect, in the OG S;G, he's outlandish, and downright embarassing for a lot of people to be around with. In zero, he's a lot more gentle but is extremely depressed and wears black attire all the time. I just wish that this was the predominant conflict than the other stuff that happened. S;G has always been a psychological anime that focused on its characters. Should stay that way.

In conclusion, Steins;Gate 0 is a disappointing mess of an adaptation, leaving a mediocre anime that fails to revoke the same themes that its predecessor has left. I'm just hoping that once the new spiritual successor VN of Steins;Gate comes out, it gets an adaptation better than zero or the original.