It's not that hard, really, once you figure out the formula. Begin with the outer edge, and start with there. begin with pieces that you know HAVE to be a certain direction, such as the + symbols. Fill those in first because there is only one solution. Don't be afraid to mess up the progress that you have by trying out new formations. Have fun!
I think it has really cute graphics. They are so adorable! the boom sound was WAY too loud and unpleasant though. I kind of liked the kiddyish cartoon quality to the scrolling backgrond.