I played Crush the Castle one and two, and honestly, I think the physics work better in those games than Angry Birds (now that I've had the chance to play it for a little bit). Angry Birds is fairly boring in comparison to Crush the Castle too. I was able to play Crush the Castle 1 and 2 all the way through due to new projectiles fairly frequently, intricate set ups that took some aiming in the skill. I mean, in Angry Birds, you just pull it back and choose an arc. At least in the flash game, you have the strategy of choosing how much power goes into it.
I don't see the appeal of this game. It's not only a rip off, but the developer thinks he's a god of game development for making something popular on the iDevices which for the most part, only has lots of ported flash games, or games equal to the entertainment value.