This is a review from the perspective of someone who read the comic. The core plot remains unchanged, it is a very interesting and unique super hero story involving time travel with a villain protag. They changed a bunch of things around (Seems mostly minor) Most of the humor is gone which sucks. The teenager's designs are all changed, they now look like generic idols/models (Qiaoyi has the biggest changes because she's much taller and less childlike). Their future selves and other adult characters look very close to their comic counterparts with slight realism tweaks. The animation is amazing some scenes, terrible in others (It does flip flopscene to scene from bad to pretty good [I'm guessing the animator skill level varies greatly]). The intro theme is actually amazing too.
The humor was one of the best parts of this series, that loss loses the 3 points. I would have preferred the designs left unchanged too because random pretty boy #32 is not interesting.