I am running both N900 and a Nexus One (not Droid, but maybe relevant to this discussion) with Froyo (Android 2.2) for a few weeks to decide which to keep. I am running the Nexus One for about 2 weeks, then will switch back to the N900 for a week or two before making a judgement on which to keep (or whether to keep both).

Initial impressions after 5 days with the Nexus One w/ 2.2:
- performance is great, extremely snappy, no lag like I sometimes get with N900 while multitasking
- very mature OS, lots of little touches missing from Maemo
- miss the real keyboard on N900!
- missing the accuracy of the resistive screen, esp. when trying to click on small links in the browser without zooming. also miss being able to use stylus to write notes quickly
- MicroB is a great browser. Miss it on Android.
- Clearly developer momentum is there with Android. Lots of good commercial apps that are just missing with Maemo that I enjoy using (e.g., I have a Rhapsody subscription, and it is great to be able to use on my phone)
- Email is vastly better on the Nexus One.
- Miss near universal cut and paste on the N900
- Miss simplicity and effectiveness of the maemo dashboard for multitasking - kind of clunky to switch apps and see what is currently running on Nexus One
- Miss integration of Skype and IM into contacts and the phone app
- Phone app way better on Nexus
- Desktop and car dock are great for Nexus One. Of course if I wanted an ecosystem, I'd get an iphone.
- certain tasks are really efficient on the N900. E.g., being able to open the keyboard and type the first few letters of a contacts name is awesome

My key reason for considering Nexus One was related to (a) poor email experience on the N900, esp. Exchange and IMAP implementation and how slow it is to switch mailboxes, a task I perform many times a day; (b) the rate of OS and app development and total lack of confidence in Intel's ability / track record on delivering software - Meego was a big confidence hit for me in future of the platform; (c) lack of developer interest and investment in Maemo platform. But email was the big one - I'd probably never consider a switch if email was on par with Symbian (e.g. if Profimail was ported and Nokia had implemented Exchange with something close to Symbian implementation or even close to competive platforms.).