So let me chime in here.
I picked it up last week for $19.99 at Gamestop. I run it on my new Dell Studio Laptop...when I bought the laptop, I upgraded to the ATI video card and added RAM to bring it to 4 GB.
With some tweaking of the graphics, it runs pretty well. I've borrowed a friend's PS3 for a long weekend and yes, it runs smoother on that. HOWEVER, again, considering I'm running it on a laptop, I'm impressed with the framerate and detail level.
Multiplayer on PC....I've dipped my toes in the water and there's LOTS of people playing. Quite the riot, even though I stink in deathmatch.
The storyline is very good, I've just unlocked the middle island.
In short, if you like the series...go for it. Especially since the price seems to have dropped recently.
Oh...and the ability to import your MP3s for the Independence Radio station is key. I'm up to 135 tracks already and have barely touched my collection.