1. Why don't all computers boot in 5 seconds? In future, there's no way I'd consider buying any mobile device which isn't flash memory-based.
2. Management of screen real estate is crucial for mobile devices, and small screens make you hate sites with advertising, especially banner ads. One touch in the wrong place and you have to trek back to the page you want.
3. It's a shock to realize how prevalent Flash interfaces and web devices have become.
4. RSS: i.bloglines.com is great, Google Reader mobile is good (probably reflects my personal preferences).
5. Surprisingly, the mobile email experience has not been as good as I expected. Gmail is a slight disappointment, but UoL Outlook Web Access is surprisingly good (sorry Martin :-)
6. Mobile note taking - I still use Gmail. The iPod Notes application is only useful if you always work from the iPod and don't change devices. Gmail is omnipresent. As expected, the iPod is great for management (e.g. posting, spam, etc), difficult (but not impossible) for writing.
7. It took me a while to figure out how to use del.icio.us easily on the iPod (sync Safari bookmarks through iTunes). Welcome back del.icio.us, I missed you :-)
8. What's the killer app for the iPod Touch? Twitter, of course. Google Maps is good, especially the mock GPS, but spooky. Google is tracking me!
9. Lack of copy and paste is a problem, e.g. for tinyURL, etc, so I installed iCopy, which is a bit of a pain, but better than nothing.
10. Summary: No regrets, except that based on this experience, I'd consider going for the iPhone over the iPod Touch. I don't need a phone but the extra connectivity is very useful at times when there's no wifi around. Having said that, I'm happy to wait for the 3G iPhone which is just around the corner.
Update: The iPT has finally converted me to using Google Calendar, now available wherever there is wifi, and the mobile version of GCal works very well on the device.