I say get it. I've had a ton of fun with it. Check out videos and the main thread to help you make up your mind. Don't let the sale pass you by.
I have also had this one on my watchlist for some time. Can anyone say how the situation is now and if it's not too buggy? Edit: i got it and just completed the first chapter. Fun game so far and definitely worth it at this price I think. I did not encounter any bugs so far.
I have a feeling the problems mainly happen if your device is quite full because iOS will delete some of the files the game needs when it needs to clear space. After I upgraded to a 128gb device I've had no problems with the game.
