If I hadn't already got a ceramic white one from Play-Asia for $56, I'd be all over this. For an extra $6 I'm happy to get white instead of black, you know, something different. Works like a charm with the American PS3 too.
As for the rumble, I've only used it with Resistance so far (I have Warhawk, Ratchet & Clank, Folklore, Motorstorm, Uncharted, etc. but I haven't tried them yet). The rumble in Resistance doesn't knock your socks off, but you know it's there. It adds to the experience a little bit, but my first impression is that the 360 controller's rumble is definitely stronger.
I really like the extra weight though. It makes the controller feel a bit better in your hands, and it's not quite as heavy as the 360 controller. Why Sony waited so long to bring these out over here I'll never know...everybody should have imported these months ago just on principle. I'll probably import a second DualShock 3, maybe in silver, so that I have two rumbling controllers.