I bought this game for a sporty 6 year old after reading other reviews. She caught onto the game immediately and the set-up was easy. The games are perfect for getting her heart rate up as well as mine! The majority of the games are very intuitive (jumping, running in place) and activity can compensate for a lack of coordination. A few games require a little more coordination (hands/feet) and can be a little challenging for a 6 year old. In the two player mode, both players can often play at the same time, eliminating the need to wait between turns and making the game a shared experiences. Games requiring team work are fun and adults can discreetly help out younger players if necessary, by stomping on arrows on the other side of the mat.
In the "free play" mode, individual short games can be selected for quick play. The game integrates short breaks into the game play - the characters celebrate shortly and you can see the stats for each session. With repeated play, new levels of difficulty are unlocked. New costumes for the characters become available - a great incentive for a 6 year old girl. Even then, water breaks sometimes need to be encouraged.
If you do not take yourself too seriously, this could be a great party game for adults as well. The game works best if you do not have downstairs neighbours - the vigorous stomping could become disturbing!