Nice, I like my PS210(s) a lot. I run a pair of them in my HT. I have a pretty large room and they fill the space nicely, are good all around for music and movies, and are pretty detailed for ported subs. Mostly what you would expect from Infinity. A nice wood enclosure that looks good with the grille on or off, not one of those cheap plastic jobs usually suited to computer or bedroom use.
I would think for a space like a bedroom, one would be more than plenty.
You may see some reviews that call the quality of this unit suspect. If you read more closely you will see that most of these folks are "wall shakers" and this sub was not designed to do that. Unfortunately they designed the electronics with enough headroom so that it could be abused. If you crank the volume to 10 and run it that way for extended periods, people claim they break in a year.
For me, if you set it up properly, you should get many years of enjoyment out of it. I intially set the volume to about half, and the crossover frequency at about 110 Hz and tweaked from there. I ended up with the volume at about a touch more than half, and the crossover at about 100 Hz. This unit is flexible enough to accomodate just about any setup.