I've been stuck with it for two months or so already, though, and it's been consistently updating. It's gotten a little better than when it first updated for me, but I still hate it.
For a while, you had to take a roundabout way to see PMs or comments, because there was no notification thing that showed up on the homepage. I think it does it for PMs now, but not comments. (I don't know about other inbox activity.)
It really helps now that the list of playlists is back on that top bar thing instead of just showing your connected accounts, with a direct link there and stuff.
I'm subscribed to near a thousand people (mostly UTAU people). I don't like seeing anything other than uploads, and by default, you see everything (likes, comments, favorites, uploads, playlists, etc). And if you wanted to change it (I don't know if this has been fixed, but it was a problem when it switched on me), you had to check everyone off one by one saying "Show only uploads". The Uploads Only tab didn't exist when it switched on me.
I also hate how recommendations aren't in their neat little side bar that could oh so easily be ignored. YT logic doesn't help in the VOCALOID fandom much for me, since it's more like "Oh, you liked this video, have a different reprint of the same video!".
I wish there was a way to make the Uploads Only tab default. I'm used to just re-clicking the YT logo to refresh the page...;;
I like the look of playlists a little better now, but I hate that you can't delete while watching videos too. I also wish the Watch Later list worked like a playlist again. (They've added the ability to manage the watch later list, it looks like too. And there's a play all button, but it's a slightly roundabout way to get there.)
I don't like how embedded videos autoplay, especially when you have five or six videos trying to play all at once... (I'm also glad that they cut the idea of Related Videos popping up in another box and playing at the same time as everything else. It did that for maybe a week.)
And also, annotations have been down for a while. (I think all of YT was affected.) The annotations button on the video player seems to be gone, and the annotation editor never seems to load.
Getting rid of the Search By Upload Date is annoying too, but I think it was Aline who mentioned you could just go in your history and use the same link, and the filter still worked.