I know another person with the D3 who has trouble getting out of 'sleep'. It'd just be really glitchy sometimes. Perhaps that was fixed with the update.
I don't think I've ever used it and am having a hard time imaging when I would.... Does anyone here use it a lot? The standby time is quite good, I just don't see the point. Perhaps on an airplane where it would save me the 10 extra seconds of booting back up at 10,000 feet....