I've got one in my bedroom and it's noisy and it smells. Oh no, wait that might be me.
Seriously, they are noisy, especially in the room underneath and you'll also get noise transmitted through the floorboards which may bother you neighbours (if you have any). The noise is mostly through your footfall. I do also find that the bedroom tends to smell, which I originally thought was sweat, but now think it's mostly the belt (I actually googled it and it seems a common problem). However there will always be the sweat side of things as well which isn't too pleasant to think about.
I always run with the bedroom windows wide open and a couple of fans pointed on me.
My bedroom floor is carpetted, and I've set the tready up on some folded carpet on top of plywood boards (to spread the weight acros a few floorboards) so it's sat on on 5 layers of carpet and some 3/4 plywood.