I'm going to be honest, my views of this anime have been badly distorted by the hype surrounding it. With dozens of people on social media calling it the greatest anime of all time, I can't help but spite it a little. I'll try to be fair in my review, but give all my ratings maybe a 1 or 2-point margin of error. Also, I'll be using 5 as the average, so just because something's rated 5 doesn't mean it's awful.
Tower of God is an anime about a boy who's only goal in life is to find his first friend, who left him to climb the tower that will grant any wish if one climbs to the top. On every level of the tower, there are tests, and one must pass these tests to advance onto the next level. It's a very simple plot that allows for near infinite stories and experiences.
Story - 7 Good
The story is incredibly simple, and it works pretty well. It's really nothing you haven't seen before: Weak protagonist gradually learns more and more and gets stronger as time goes on. However, the enormous world the characters are put in expands on the plot much more than other similar shows, which is this story's greatest strength.
Art - 8 Very Good
The art is gorgeous. It's not a typical anime style, but that doesn't make it not beautiful. As many others have said, it's based off of the webcomic's original artstyle, and Studio Telecom did an amazing job with it. The one thing I do have a slight problem with is the animation. Most of it is fine, but for an action anime, the fight scenes are kind of lacking. I'm aware that most anime put the same amount of effort into the fights as Tower of God, but that just means it's average. Overall, though, the art is really good.
Sound - 10 Outstanding
Yeah, Kevin Penkin is a god damn genius. I don't believe I need to say any more.
Characters - 9 Great
The characters are all so lovable. Khun is a fascinating evil mastermind and Rak is the incarnation of bro energy. Even the side characters are amazing(looking at you Shibisu). The one and only complaint I have is for the main character, Bam, and his first friend, Rachael. Bam really isn't all that interesting. His goals are weak, he only kind of has a personality, and his entire character is centered on Rachael. And Rachael, oh boy. She's equally as boring, but with the added bonus of being a prick. Still though, every other character is amazing.
Enjoyment - 7 Good
There's really nothing wrong with this anime, it's just that shounen isn't exactly my cup of tea. I'm never bored watching this anime, I can tell you that, but I thrive on deep emotional conflict, which simply doesn't exist in Tower of God. Anyways, it's really enjoyable. Even a shounen hater like me can enjoy it pretty well, so you'll definitely enjoy it.
Overall - 8 Very Good
Overall, Tower of God is a very good anime. It's kind of like Demon Slayer, where it doesn't invent anything new, but it masters all the tropes it was given. And also like Demon Slayer, it is not the greatest anime of all time. Please stop calling it that, I beg of you. You're just going to ruin other's perceptions of it. Anyways(sorry for the side tangent), I would definitely recommend this anime. The pacing is really good, so enough happens in the first episode to give a nice little first impression. So watch one episode and see if you like it.