Across the top number keys are a set of iPad-specific functions, activated by holding down Fn on the lower left and pressing. The 5 key doubles as a picture-gallery shortcut; the 7, 8, and 9 keys alternately rewind, play/pause, and fast-forward music tracks; volume controls are on the end. These basic functions mirror what's on other iPad keyboards, including Apple's. A search button is tucked away to the right of the Option key, and it launches Spotlight search. Alas, you can't keyboard-click searched-for apps and documents--you'll have to tap on the screen. A Home key on the top right works like the one on the iPad.
You could also use the Logitech keyboard with an iPhone, if you so choose; iOS 4.3 supports keyboards, and we were able to use it on our iPhone 4 without a hitch. Music and volume controls worked, too. You could even rest your iPhone on the elevated stand. It's an odd pairing, but doable.
Logitech's keyboard is high-quality, too. We used it to write this review, in fact. It feels great, with every key being where it should. The direction-arrow keys also enable zipping through docs without reaching up to touch the screen when making line edits. That's the difference in our opinion between a keyboard case and a full keyboard like this one: writing on a full keyboard makes the experience feel nearly indistinguishable from sitting at a computer.
The fact that we wrote this whole review on it and never got tired is the best recommendation we can give. At $69, this keyboard's well worth the money, unless you prefer Apple's solution and don't mind forgoing the stand. Think carefully about that choice, though; a stand matters more than you think.