So far it has been great. It has responded well to everything I asked of it. I don't quite get the boost I'm used to when passing, but I'm used to V6's anyway, so any fuel-efficient four-banger would be lacking. I decided against Civic because of the interior size (the Prius mid-size interior is big enough to put the kids in the back seat without them automatically kicking my seat), in the end the only major runner-up was the Matrix/Vibe, but it had too much of the "4 cylinder noise/vibration." The Prius has some of that noise when accelerating from stop, but once the CVT "shifts" and the engine revs back down it's a nice, quiet ride. Handles highway speeds with ease, and no, it hasn't stalled. (TSB applied to cars made up to the month before mine was built).
Thanks for asking!