Makes YouTube almost unusable: adds a considerable delay to every UI interaction. For example pausing or resuming a video takes 5-20 seconds.

FOSS and saves your time, great.

Saves so much time. No random YouTuber I don't care about your sponsorship for a drink, a service or whatever else I just care about your content

I'd never use youtube without this.
Segments can be a bit overzealous. I'm surprised by what gets upvoted sometimes. "Highlights" in particular are just confusing more often than they're useful IME (why would anyone want to skip the first 10 seconds of Old Town Road?), but it's more of a problem with categories that you might generally want to autoskip, but sometimes have segments that don't fit the category rules.
So, this is a bit more of a compromise than traditional adblockers are. But I'd rather occasionally hassle with unskipping a segment than ever hear an ad-read for a VPN ever again. It's a net positive by a huge amount. Thank you Ajay and everyone who tags segments.

This brings things back to normal. I'm sorry to all of the creators out there, and I understand that YouTube itself doesn't pay you enough through ad revenue to do what you need, but if I see another NordVPN, Manscaped, Audible, or World of Tanks sponsorship again, I will defecate myself. I love you Ajay.

Absolutely essential

This extension does what it claims to be, but there's one issue on the mobile version. When I'm watching a video on full screen and if that video has a sponsor part, as soon as the video comes to that part the extension is forcing the player to exit the full screen.

genuinely a necessity, never experienced any glitches or bugs