People have 'problem' with N900 because they expect features of a smartphone within that form factor. Something they can pocket all day long and execute some quick tasks on... those tasks that have been popularized by the form factor since the Palm Pilot days (PIM functions) and extended by the latter smartphones (Media and Internet functions).

"B-b-b-but N900 is so much more than that...!"

Yes, I think most people have thought about having pocketable computers which can interface with full featured input/output peripherals, but this does not alleviate the need for the quick & simple common tasks when they're on the go. Sure, this can be addressed with widgets or some implementation of alternate & simplified front end to the same app; as long as they still perform things quickly and simply.

Right now the N900 is neither a good smartphone nor an adequate pocketable full desktop yet (lacking good I/O and general horsepower as a desktop... and limited software selection).

So there...