The controls are simple and intuitive: swipe to move/attack.
The controls are easy to master, and after the latest update, the full game is available for free with the option to buy certain items with real money. (IAP = In App Purchase)
The graphics are silky smooth on most devices, considering it is a 2D game, mainly platform-based. The more expensive your device is... Undoubtedly, the better it will handle games like this (high frame rates, multi-thread RAM activity, etc.). But, on the other hand, I used a tablet that was marked down to $40 on Xmas last year and it performs way better than I initially expected. So if you have a phone that is more than $50 (not Chinese branded), you most likely have a Samsung, LG, or Motorola device, and every phone from each of these competitors are more than capable of giving you buttery-smooth gameplay.
If you have any questions or comments, please state your thoughts on this thread and I'll respond ASAP. 
