on one hand, people say it enhances their experience, i think someone's said it's more user-friendly or something, it's improved some performance on programs, some stuff about direct x12, overall good things, start menu too if you're big about that thing
on the other hand, it's still pretty buggy, (
https://forum.blockland.us/index.php?topic=300615.msg9170635#msg9170635 ), people reporting stuff using up 100% of their disk, their computers slowing down, performance being worse, programs/things getting corrupted/becoming incompatible after upgrading (rare though iirc), advertisements being put up in places they shouldn't be (i.e. start menu), and if you're a tinfoil hatter there's a lot of criticism about user privacy in windows 10 but i think most of it is optional
also, if you use it, they get rid of these features from the calculator;