I wouldn't upgrade to Lion mostly I'm still dependent of PowerPC apps such as the older iMovie. The fact that it's only available via download, and you have to go through the whole disk burning, putting it on a flash drive headache if you want a physical copy doesn't exactly appeal to me either.
Never having used Lion, I can't exactly say from an experience standpoint, but this is the first Mac OS update that my first impression was "I don't even really want to upgrade if it was free" From what I've read, and researched, I suppose Apple is trying to incorporate more gestures to make stuff easier, but I never even used expose on 10.5 and 10.6, why would I want to four finger swipe or something like that on 10.7?
Again, maybe I'm wrong, maybe Lion is totally amazing, maybe I missed some ground breaking new feature, and it's just because I've never used it (or even own a computer that would run it at the moment) that I'm underwhelmed with Lion.
P.S. I'm writing this from a laptop running Windows Vista, and there's NO WAY that 10.7 can be this bad.