The vkb is much better than on n900. But still I am not fully used to and make lots of typos. There is also Swype available.
But there are no buttons for left/right/up/down. And again there is a tweak for almost all kind of keyboards available (I am using mainly n900 layout de/en).

The read-only on n900 you mention is just a file system prob (not really a prob). I am talking about real failure of flash memory.

RAM is much more nice but still we can get to the edge.
There are tweaks for sharing mtd4 as additional swap (but did not bother to do so as I used mtd4 for ubiboot). And it will burn the ubi system on that partition.

HW buttons? What for? All is swiping here!
Camera I would say is on pair (since n95! ).