All very well and good, BUT I think samsung have got it right, who really uses 3g at this point in time? Very very few people bar some mobile internet folks. No one uses video calling really, if they do its for a few calls for the novelty, then its back to using the phone as a phone. The cams on them are both 3mp, the sony may have a suprior one, ill have to see the reviews, but its not going to be a massive jump what so ever, played with the d900 in the shop yesterday and its cam to me look the same as the k800 at the same zoom level of the same shot (basically it may have better specs, but to the end user they looked same, like comparing a D50 to a 350D, one may be technically better but for snap shots they look the same, lets face it your not gonna use your phone to take serious photography) And to me the k800 is aweful, the menu is the same as the samsung a icon display you move around, apart from the k800 is hugely let down by that god aweful mini joystick, had a couple SE after a year they all broke. i.e. that darn joystick stopped working. Another thing I noticed while using both phones at the same time is that the software on the d900 was much quicker, the SE had noticable 'load' times, i.e. took a couple seconds get into menu area for txts, games etc......same as the old 610 i used have.......sort it SE !. And finally as already commented on its size, for what it packs.....humm ok, but my old phone is still smaller than it, way to big, d900 perfect size for new phone. A personal opinion/review here but for me SE need to sort all the joystick/load time/useful features/phone size issues out.
I've never actually seen the E900 in flesh so it was difficult to make a firm comparison. 
Although if you're buying online I'd recommend 