There are two versions of the app - a free one and a paid edition (for £1.00) although I can't see what the difference is. Both have the same three levels - so for now I would stick with the free one. The game is probably targeted at kids and they will love it for sure, however there is something strangely satisfying about the game and I found myself getting quite into it.
The gameplay is smooth and the graphics are decent, however sounds are limited with just the occasional noise when a zombie chick hatches. It would be nice to have some funky music to play along to. For a free PlayBook download Bag Egg is worth checking out. It may not be the most exciting game but for killing some time or keeping the kids entertained it is perfect.