The Acer Aspire One is one of the best netbooks I have ever tested. As a computer person, I am always looking for new laptops, desktops and netbooks. When the AAO first came our, I was pretty skeptical on how it was going to run, and considering its selling point was the battery life and weight, I didn't think it was going to be a netbook I would like.
When I tested it out, the AAO booted up pretty slowly, and you had to wait a while before the internet could be opened. The computer felt really light on my lap, but after 4 hours of using it, it became extremely hot. The battery life on a full charge lasts anywhere from 7-8 hours, sometimes you can even push 9. The 250GB Hard Drive wasn't to bad also. The CPU is sometimes slow, but with no background programs running, programs open nice and smooth. The screen size can be a bit annoying at times, sometimes I even had to zoom in with the track pad. The trackpad features aren't great, but they are okay if you want a new way to do something.
This netbook obviously wont be able to handle games, but I run Eclipse and create Android Apps with it all the time with no problem. I recommend getting a mouse if you are going to be using it for work, but other than that, I think it's a buy if you are looking for a netbook.