I started playing with this app on Saturday and I struggled to put it down. Don't ask me why though. I just think it's amazing. It's one of those somewhat rare apps that just grabs your attention, or at least it grabs mine anyway.
It reminds me in many ways of the apps from the Strange Agency. In fact, it reminds me of their apps a lot. So that'll probably give you an idea as to whether or not it's the kind of thing you might like.
Anyway, to help you make up your mind here's a video:
For a $3.99 app I'm not sure you can get much better than this. I think I'm going to be playing with this for a very long time.