Cute mouse, arrived quickly and really easy to get going. You just need to remove the receiver from the underside of the mouse and plug it into the computer, making sure you have the batteries installed correctly. Ergonomic shape is good, and it is comfortable to use/handle. Only slight criticism is that the mouse doesn't work on every surface I've tried, and performs better on dark surfaces than reflective ones. Also, the side buttons could be a bit stiffer in my opinion, but useful to have.
I'd also recommend their blue wireless mouse
which is a bit cheaper and performs nicely, too.