I can't say they're for the better. As far as I've noticed the changes to YouTube include a slightly redesigned main page, which more or less works well and is just as practical as the previous version.
Then there's the Recent Activity, a new profile feature that mimics Facebook in that it constantly updates with what you favorite, comment on, subscribe to, etc. And it also allows you to type in short messages of what you're doing, much like Facebook or Twitter. It's an OK feature I guess, but I don't fell it was necessary for YouTube to add it.
And the last thing I noticed is my least favorite upgrade. If you haven't noticed already, all embedded YouTube videos now have a huge search bar on them. It's not in the way when viewing the videos, luckily, but it's kind of ugly to look at in the middle of a blog.
These are just my opinions though, what do you think?
UPDATE: More things I've noticed, account options are slightly modified, and time stamps now appear on video thumbnails. And that huge search bar I was complaining about is now slightly less bulky and features a transparent background instead of the bold silver it once was, and only shows up when you mouse over the video.