SSSS. Gridman, what an adventure. I'll try to make this review as spoiler-free as possible.
From the show's relatively humble beginnings to it's grandiose end, it's was excellent all the way through.

SSSS.Gridman is an amusing blend of genres, putting one of the spotlights on the school life aspect of it's main cast but driving itself forward through both elements of Mecha and Kaijuu tokusatsu shows. It's the perfect transition to animation an original Henshin tokusatsu show could ever ask for.

Every episode is littered with great cinematography, art and animation accompanied with high energy tracks that compliment the production.
It's filled to the brim with 2D sakuga and fluid CG animation which shows just how passionate the staff was about the whole show.
The atmosphere's carefully crafted by the proper use of soundtracks and effects combined with the cinematography consisting of airless, sort of confined shots of the blistering summer heat and oppressive cloudy rains. It gives the show a sense of an identity that a lot of recent anime just can't seem to grasp.
The sound design is especially amazing at giving audio feedback during these scenes, a vehicle being crushed, the ground crumbling under a monster, and all of the attacks sound so visceral and lifelike.

The story is rather formulaic as it sticks to a Monster of The Week format but the archetypical structure of the format is broken down in a few places, making way for an actual overarching plot within the setup.
Every plot point the show setup was unveiled at a proper pacing, and while the characters lacked development outside of Akane, the underlying themes still got through and eventually culminated into it's fantastic ending which saw Akane finally facing herself instead of finding fault in everything else.

The entire roster is colorful and visually distinct, making them easy to remember, and potentially iconic - someday, down the line.
The development for Hibiki, Rikka and Utsumi did feel kind of miniscule in the grand scheme of things and they should've gotten more screen time addressing their personal characteristics but the main focus of the plot didn't really require much on that front so they can be given a pass.

Overall it's a great show that's totally worth everyone's time and attention.