Wii Play is fun while it lasts... and that isn't very long.
Wii Play makes a big use of the Miis and pulls it off quite well - it is fun to see your own Mii riding on the back of a cow or being told to find one of your friends or family in a bunch of loads of other Miis. Wii Play's games are mainly mediocre, with a few semi-decent ones and a few being just plain awful. The highlight of the whole package is the billiards which has the most thought out and planned controls - however, I did find the pushing the remote forward to hit the ball a pain sometimes as it wouldn't register the movement because my arm wasn't dead straight. Apart from this though, the game is good.
Games such as 'Find Mii' and 'Pose Mii' really get boring after a while and you don't feel any urge at all to go back and beat your score, mainly because it is just so repitive. The tanks game is another highlight, the only game to use the nunchuk (optional, but I would highly reccomended you do use it) which sees you shooting down enemy tanks on a flat 2D maze landscape.
For £5 the game is decent and you may as well buy it, and you may as well by it if not only for the controller. However, this could have been better and you do get the slight feel of it being rushed.