I have a late 2010 model 13" macbook air (the "old" new air) with only 2 GB of RAM. I read a lot of mixed stories about upgrading from Snow Leopard to Lion but finally decided to take the plunge. My decision was based mainly on my desire to have full iCloud integration with my new iPhone. I'm very very happy I made this decision! The download and install went seamlessly well, and I really like the new look and feel. Native apps like Mail and iCal look so different it's almost like I got a new machine. I dare say most apps are running better and faster after the upgrade, which was a real surprise. I've tested pretty much everything I use regularly (MS Office, iTunes, iPhoto, Firefox) and so far so very good. The reports of lags during shut-down and boot-up did not happen to me, either. There are a few features that I didn't know Lion had that I really love now, including the ability to boot where I left off before shut down with all my apps and their respective files already open. So I just wanted to say, if you are like me and hesitant about the upgrade that not all the experiences with the upgrade (no clean install for me either) are bad ones.