If you liked Wii Sports you'll love this follow up!
As the official review says, this game is much better served with 2 or more players, but offers hours of fun for family and friends. As with all games like this some of the mini-games are better than others. I have been playing this with my wife and 4 kids (aged between 12 and 3) and there has been something for all of us. The games that offer huge competition and thus replay value include Archery, Frisbee, Basketball, Table Tennis, Sword Play and Golf - none of these are over complex from a control point of view and my 3 year can hit the target (some times) in the Archery unaided whilst my 12 year old is challenging me for the top spot on the leader board.
A couple of the games including the Cycling are a little more hard work to play (I noticed the cycle course being the same (or very similar) to the longest jogging route from Wii Fit) since the game consists of waving the Wii Remote in one hand and the Nunchuk in the other up and down to pedal. This doesn't feel quite so fun.
If I have one complaint it's the decision not to ship the game on it's own (I already had 2 motion plus controllers from playing Grand Slam Tennis) without the motion plus, although as it turned out having a third one was useful in the end.
In summary then a great addition to the Wii especially for those rainy Saturday afternoons that here in the UK we will inevitably get all through August!