This isn't a bad controller for the price. I managed to get mine for £10 so very cheap in comparison to the official controllers which generally cost about £40.
The problem with this controller is that the buttons are quite chunky, you have to press them down harder and it just isn't as smooth to use as the official controllers that you will be used to. This is ok for the casual gamer like me, but if you are planning on using this controller all the time or for games that require quick reaction times I could see it becoming annoying. Another problem with this controller is that you have to use AA batteries in it, which not only is a pain in itself but also means that the controller is alot heavier to hold and alot chunkier.
I haven't had any problems with it working so far and it was easy to connect so no issues from that perspective.
Overall I would say that for the price this controller is definately worth buying if you are planning on using it for casual gaming or as a spare, if you're looking for something to use all the time that's smooth, light and good for quick reaction times then it's probably worth spending the extra for an official one.