Hi stayloa. Got no problems with my N900 yet too! I've never needed to reflash it, it has never rebooted by itself (ok actually just once one month ago and never again, so it is approximately NEVER), it has never had non-working apps installed so far, all seems working great. I've installed about 15 apps from extras-testing and devel, I've freed up my rootfs reinstalling the optified version of python (I had about 90% filled up rootfs, but now just 80%) and I've been able to update my firmware OTA without any problem.
I've used X-Term for modifying boot video, leds' colours, for installing some extra apps from .deb files (e.g. 7zip and ScummVM) and for using apt-get/cache commands for searching/downloading applications easily without app manager.
Until now the only and major problem for me is that after every boot it switches back to the default theme if I try to use some of the OVI themes, so I feel lucky.