It depends on a couple of things. First one is wether or not you attempt to run it with 2GB of RAM. If you do, you may be asking for a headache... it doesn't run smoothly at all on a 2GB system. Upgrading to 4GB is quite cheap and if you do that, it will take off.
The other thing is wether or not you're OK with iPad-esque features. Personally, I'm ok with most of them: Mail is fabulous, Launchpad is a great and useful idea (although it still needs work and customization options) and iCal despite the GUI which so many people hate but which for me is completely irrelevant, as the app itself is VERY GOOD.
Other than that, after a couple hours run, Lion is incredibly fast to open everything. Most apps only bounce once before launching.
I believe that by 10.7.1 it will be a redefining OS. ".0" is just good enough to avoid Apple a lot of headaches. I did think it would be Apple's Vista, but it's just too stable and fast for that. The user experience is quite simple and intuitive and also, it doesn't throw security questions in your screen every 2 mins like Vista did.
The only other thing I think still needs work is the animations' fluidity. Sometimes many of them are quite choppy.