By comparing with my current phone (SE K750i) I think that the thickness of the N900 will not be a problem for me (the SE is 20.5 mm thick!). What I'm more worried about are the other dimensions, since I usually carry my phone in my pocket and I'm not really a big fan of huge pants pockets

On the plus side, no need to carry both the N800 and the cell phone, which is quite good!