If you are going to get an Air, I highly suggest you go to a Macbook instead. The Air is great, but it can be better. Now if the Air isn't going to be your only computer then I would think about it. I have an iMac and used a Macbook and then a Netbook for a while and realized I didn't want two computers. I would rather have one computer and one device that allows me to consume media in a cooler way.
Some people need a laptop, others need a secondary "computer" but not a full fledged one. The iPad works well for what I bought it for, much better than the netbook I had. I use mine for checking my email, browsing the web (saves energy versus doing it from my computer), watching movies, playing the occasional game, and inputting data into a simple spreadsheet.
FYI, I'm a spreadsheet junkie and the way iPad has "Numbers" set up is kind of annoying but it works, especially with the bluetooth keyboard. It's nice when I can decide I want to track something differently and be able to do it right then and there, not when I get home or get to the office. While it's my toy I actually get a lot of use out of it at work.