I own the rumble pad, so I can tell ya a couple of things about it.
The good:
It has some vibrational feedback - but especially for racing it won't do much..
It's got two analog joysticks - excellent
The bad:
The keypad cross on the top left sucks rotten boulders. I swear. So, platform games are a no-no with it.
I don't like the software that comes with it! It's better to customize in game.
I bought it because I thought I would rock Descent 3 with two analog sticks. I was wrong. I am much better with the keyboard. It's a decent buy for the money, but I would not recommend it for most games.