Quick impression for Mint 10. Like Mint 9 it is still a derivative of Ubuntu (I don't think it's running Unity though). On the machines at the lab it was pretty fast. Given those machines are at least five years old that's saying something. Compared to Mint 9 it is slightly slower. According to their web page most of the changes are superficial apart from additional codecs. It looks like they've put some effort into the eye-candy. The green is gone and replaced with grey. Given what was installed in Mint 9, I'd say this is more of something for the end user as opposed to a developer. This is something you could show off to the boss for their home machine.
Since it was just released on Friday I haven't had much of a chance to stress it any. If anyone is looking to get it, connecting to their web site may take a few tries. Given the connection issues, my suggestion is to grab the torrent files for download. They take less than an hour for the DVD at this point. There is also a CD version which is slightly smaller than the DVD version.
Later Mike