I actually ride this exact bike. I don't know too much about bikes but all I know is I'm extremely happy with it. I did bend my back rim, but I either did that in my poor attempts at learning to bunny hop (I'm better now though) or taking it downhilling at Whistler (boy was that fun... not as much as the XC there though
). Either way, I've put some abuse on it already and it's holding up great so far.
As far as seats go, I've ridden dozens of bikes, and lets face it... after a hard day of riding your ass is going to be sore. If you find something comfortable, great, but I wouldn't pull your hair out looking for it. Although if you are looking for an upgrade, I'd recomend clipless pedals, takes a bit to get use too but I love mine.