Cliffhangers are a common way of leaving an update. They get you looking forward to the next release so you can find out what happens, and they get you talking until then. There's nothing wrong with using them. Obviously some people will get a bit mad - but it's almost always going to be because they don't want to wait, they want the answers now... which is one intention of the cliffhanger, meaning it's doing its job.
I played an update of a game a while ago and decided I had had enough and was going to drop it, but there was a cliffhanger at the end that I want to know the answer to. So now I'm waiting for the next update, even though I've already decided to drop the game...