Why I keep mine:

• screen size
• input methods
• battery life

My usage patterns mostly revolve around email/jabber/ssh and the odd web page or PDF doc (ie, reading and writing text). The available email options on all Maemo devices so far pretty much suck, but for the rest the N8x0s are still the best devices currently available. I don't need a cellphone except for using as a modem, and these days a "mifi" device is a better option for that anyway.