I think people were waaaaaay overcritical of the rumble pack. It's worth having for the games it works with, it isn't nearly as loud as people say. I think it does add to the Mario vs Luigi, pinball, and Metroid Prime experiences.
Here's the details on the free rumble pack by the way. Looks like it was a limited-edition retail bundle, not a sendaway. I can't say I've ever seen one, but I haven't really looked for it either.
I just wish they'd come out with the DSL version of it here already. I never use it with my lite because it bothers me to have something sticking out of the GBA slot.