Apple OS upgrade is always worth it! The only concern is whether or not your current Apple computer is robust enough to handle the GUI interface. This is the reason why I always get the Middle Pro Model than the basic MacBook. But for the first time I'm really tempted to buy the MacBook Air 11 inch (basic model) as my traveling laptop. I'm choosing this over an iPad which basically is useless if your not connected online at least for me.
Anyway going back to Lion OSX. Awesome! Just upgraded now, and it's pretty cool.
So far Lion is working on my iMac 24.
The only problems I have had deal with permissions.
Lion has several new functions that are nice.