Good
You judge a game by how much fun it gave you and how it makes you feel playing it, not by looking back and see which game it originate from. There is a reason why game design should and will never be patented, otherwise games will never evolve. Although looks like this game inspired by the success of angry bird, doesnt mean angry bird should and must be the only one ever exist! And don't forget the fact that this game is fun, looks different and plays well.
If what you called as "Rip-off" is prohibited, we all will still playing Wolfenstein 3D until now, and Quake, Unreal Tournament, Crysis, Half life, and other great FPS will never exist. World of Warcraft will never exist and we will all plays Ultima Online.
So if you think this game is a rip-off, with all due respect please shutup unless you are still playing Wolfenstein 3D, Ultima Online, to this date and never played & enjoy other "rip-off games" in your life ever!