I'm actually not happy with it.. The UI is nice, it's fast, has a lot of storage, like the idea of running Linux on my phone... but the stuff I really need it for doesn't work at all or partially works:

- IMAP lacks IMAP-IDLE and the mail-app hangs on large mailboxes -> email is unusable for corporate use. I tried Nokia Messaging, but that's too slow for normal use.
- Can't sync contacts or calendar entries with Google anymore (worked the first week I got the device, now I only get timeouts).
- Office-docs can only be accessed by (commercial) third-party software.
- Battery-life is very disappointing if you actually use the device.
- No turn-by-turn navigation-software, Nokia Maps is not an option and Sygic's has been delayed ("because Nokia asked them not to release until more devices hit the market")

I went back to my (3 year old) E90 for daily use and use the N900 as a rather expensive mediaplayer in my car at this time until Nokia releases an update.