Oh man. That phone introduced me to the linux ecosystem at the tender age of 16. I learned to write python, C, and the concept of “on device development”. You could write apps in whatever language you wanted whilst in the backseat of a roadtrip across Europe (I was a seriously antisocial teen). Plus FM transmitter.
The best successor I’ve seen is the FX-tech Pro phone, but given it’s costly price, it’s just not worth it. I got my N900 for £230, but the FX-tech Pro is asking for more than double that…