I've had several wow moments. 3 this weekend:

We have crappy radio reception where we live, and on Sat evening were listening to a show and the reception was worse than usual on our big stereo. I opened up the N900, turned on FMRadio, pushed sound out of the speakers, and got excellent sound and reception (this is the first time my wife was impressed with the device despite my lauding its praises for a while now)

The second was more prosaic - messing around with some UI stuff in CLI I managed to put the baby into a funk from which it could not recover. I grabbed my N810, ssh-ed in to the N900 and copied the backup file back. Reboot and presto all was well. I didn't stop messing and messed it again, this into a reboot loop which meant I couldn't ssh in. Plugged into my laptop and when it tried to reboot it couldn't (connected via USB mass storage...) - then I ssh-ed in from the N810 and fixed it again. After all of which, it works flawlessly. If you're in such a reboot loop, this might work for you before flashing. YMMV.

Perhaps the most interesting was when I was using the N810 to fix the N900. The wow moment was very much along the lines of 'wow, the keyboard and feel of the N810 is very nice and I almost prefer it, but the whole package of the N900 is so much more tactile.'

Nice job Nokia...