I'm still fine doing that, and actually like having the cellular radio on a separate battery, so the real computer is still functional even if the connectivity is out of juice. I admit I don't need cellular voice at all though.

May I point you to: It is not a cell phone -- and it is good

I found a huge difference. Priority was given to making it "finger friendly" and "optimised for one-handed use" to the detriment of everything else. Input methods in particular were completely massacred to accommodate this. Then there's "kinetic" scrolling versus scrollbars, the way many apps / widgets stopped showing a lot of relevant information in order to make all remaining UI elements "thumbable" (which raises the question, what's the 800x480 resolution for?) etc.

The other side of this is the hardware, An N8x0 might be a bit large to hold to your ear, but I found the N900's screen way too small to use comfortably (and the size made all of the above worse). And the third side is that that little radio tends to turn everyone into control freaks. If putting a cellular modem into the N900 means the user has to put up with cherry or the SIM deciding which wifi channels can be seen, I'd rather not have it thank you very much.