Ah, it's kind of fun so far. I'm beginning to like Mission Control and like the way you add spaces and remove spaces, and three-finger slide between full screen apps and spaces. Some weirdness though: sometimes app windows seem to not appear "shrinked" properly in Mission Control.
Running full-screen Safari now. Feels like... BIG.

I know full-screen browsing has been around for a while, but it seems done OK in Safari for Lion.
64bit-ness feels good as well.
Hmm... Autocorrect spelling works too.
A tab was beach balling in Safari but could switch to other tabs.
I like the new iPad-like Mail layout.
Niggles:
1.
Finder windows still don't expand fully (aka maximise like Windows, yes, old habits die hard). So I still use RightZoom app which still works.
2.
Pinch-to-zoom in Safari doesn't expand text like before but follows iPad behaviour. You have to Cmd+ or Cmd- if you want the old behaviour. New behaviour is good for fixed-width kind of website text but not so good for full-width websites like AI. More on this here:
http://forums.macrumors.com/showthread.php?t=1196517
3.
A little dash of lagginess on my MBP Core 2 Duo 13" 2010 model with Nvidia 320M. But I find things pick up alright as things get cached into RAM, VRAM, HDD, whatever.
4.
Wow. Autocorrect lets you type quite fast but may take some getting used to.
5.
Bug: "When Safari and MAil is in full screen app (Lion), Cmd-I brings mail compose window in the Mail window, but Cmd-Shift-I opens the mail compose window in an unused workspace. That’s not the way it’s meant to work, so I class it as a bug." See also:
http://www.macworld.com.au/help/10-m...ortcuts-34010/
6.
Safari rubber-banding cuts of a tiny bit of the top of a web page sometimes (maybe all the time).
CONCLUSION: Unless you've got something mission-critical that you've researched will mess up bad, go for Lion. Heck, for $29 it's worthwhile entertainment, if nothing else.

You will have to tinker with it a bit to get used to it. Some features are good, some are not so polished up yet.