First, in defense of the developer, this is NOT a joystick driver or detector. In particular, it is not designed to detect your Xbox 360 Gamepad. For that, at least in Yosemite, you’ll need to get “360Controller” v. 0.14 from GitHub. Tattiebogle (either 0.11 or 0.12) will NOT work any longer in Yosemite. So lay off the 1-stars for that reason. Either Apple or Microsoft should have added controller support a long time ago, but until then, use this work around. (I had to discover this on my own, only to find out the dev points this out in the FAQ!)
But even when you get your Mac to recognize the controller, the app isn’t perfect. My main complaint is that this app is INCOMPLETE: You have to buy the separate app “Joystick Show” in order to know what any of the buttons are! Otherwise, figuring out which buttons correspond to which numbers is impossible. The “scan” feature does provide a way around this problem, but it would nice to be know what I’m mapping to what without needing a separate app. So if you consider this a SIX-dollar app (including $1 for “Joystick Show”) it’s more honest, since the numbers in “Show” line up with those in “Mapper.” But the “Scan” input feature is feasible, even if it makes you feel blind with respect to the button numbering.
Finally, beware of this app interacting badly with games that have built in controller support. It doesn’t override a game’s default controller mapping: instead, it blends with it, so that you can get mixed button or joystick mapping (e.g., a combined move/look axis), which happened to me until I figured out what was happening. And if a game already has controller support, it should work fine without Joystick Mapper--in which case you don’t need this app!
Bottom line: This app is expensive for what it does (-1 star), and especially when you realize it puts an essential feature in a separate app (-1 star).