I've been reading about them for about 6 months now and I've been tossing around whether to get one or not since they started selling. I have a Sharp Zaurus 5600 which I never use and so I figured I'd pine over but never actually buy a Nokia 770.
Then I had a change of heart. I bought one because it's easy to use, small, has a full-blown Linux distribution that takes .deb packaged files, has a great web-browser, is in constant development as an Open Source project, and someone's gone and ported Python to it.
I ordered it on Sunday and it showed up on Wednesday. I've been getting to know it for a little under a day now and I'm really impressed--it both fits my needs and extends my ability to do things very nicely. I'm planning to bring it travelling next week with a load of PDFs on it of things I want to read. Additionally, I've been able to check email which helped me get to a meeting yesterday night after I had forgotten the location.