The last heist I finished was the third one. I stopped playing partly because Witcher 3 came out when I started playing the fourth one, and that trash collecting mission was so hard, that I just couldn't bare myself to retry it one more time. I'm a little bit disappointed by the heists, since once you complete them, there's not many reasons why you should play them again. Sure, you can beat it again and try a different approach, but that's about it. Also, nobody seems to ever join my heists, and the people that join are very low level, and I am around 50 or so. I expected the heists to be a lot better, and I expected there to be more heists. Also, Rockstar has said that they won't be making any more heists since they were very hard to do, and they're simply not planning to do any more. :/