I have been using one since I bought my iPad 3 months ago. They work just fine and are so convenient to carry around. I like the soft carry case they come in too. I had the keyboard before I bought my iPad and used it with my Nokia mobile 'phone and, after I'd bought my iPad just thought I'd try it. Was surprised to find it worked first time with no problems at all.
I find fitting the batteries a bit 'fiddly', but they last a long time. The keyboard automatically goes to sleep after you've not typed for a while (there is no power switch) so, when you start to type again, it takes a second or two for the Bluetooth link to be re-established, but all the text is buffered. Same when you first unfold the keyboard and start using it. Initially the iPad pops up the on-screen keyboard. But just start typing on the BT keyboard and, after a second or two, the BT link is automatically re-established, the on-screen keyboard disappears and the buffered characters that you typed while the BT link was being established all pop up on the screen.
Tim
Scotland