I've used it to re-download my Mass Effect 2 and for getting the preorder goodies for Alice 2 and its... fine, really.
For ME2 and Alice 2 at least, Origin itself doesn't even have to run to start the game, the overlay if you use it is very steam-ish... Pretty standard stuff, really. I've browsed the store a few times, never saw anything at a good price I wanted to get and that's pretty much the extent of my feelings on it.