I've been using this for a couple of months. It's very compact and versatile, and works fine. The loudest volume setting tends to distort, but the next loudest volume setting is loud enough for most environments. I've even used it in my car when my car stereo wasn't working. It works with my 3G video iPod and my kid's brand new iPod Nano.
It's advertised as having some kind of bass-boost/woofer system but, to be honest, that's not obvious upon using it. It DOES sound a bit tinny, I'm afraid, but I think you have to expect that with such a tiny versatile unit.
I'd recommend it to any iPod owner.