I like the N900 so much, I did not bail from Tmo for Verizon (almost same price as Verizon and 3G in my town). I forgot though that I have $10 of insurance for two devices and N900 will not work with Verizon.
Actual Verizon cost would be $120 more per year.
N900 is too sexy to turn down
Besides the .2" bigger screen and compass I would not use, I am not seeing $150 more device with Droid (based on retail of each).
N900 has and Droid does not:
1. 32 gigs of built in fast memory and an sd slot (not class 2 sd card like Droid).
2. better camera
3. a LOT more codec support
4. better browser
5. not locked down
6. FM receiver and transmitter
7. OS use the dynamic scaling of the 3430 instead of capping it like Droid
8. Flash 9.4 now instead of (at least) a five month wait and N900 is getting 10.1 too
Again: Droid costs $150 more than the N900, but less an immediate issue of course with two year contract with Verizon.
Still, having wide coverage of 3G is very tempting and if N900 was Verizon 3G, I would bail from Tmo and make many people here very happy.