My daughter(8) finished this after approx 6 weeks of casual play, seemed to enjoy what appears to be a glorified tamagotchi. It's a very simplistic 'pet hospital' management game, targeted at the younger gamer. The player is in charge of the family practice, complete with extortionate fees (realistic in this sense, I guess).
Punters arrive with sick animals (starting with cats), a diagnosis requires playing a few mini games, based on scribbling, blowing, copying and the usual DS antics. Nothing like Trauma Centre's operating theatre, though, just removing the odd flea, sticking a thermometer in various places, following ECG traces, etc. The animal is then housed in a pen, til it gets better, through patient aftercare and recovery, based on feeding, cleaning (NHS take note), and playing with the furry creatures - mental wellbeing is pivotal in recuperation in this practice (NHS take note).
Cured animals command a fee, when accumulated, allow expansion to build kennels, pig pens, stables, rabbit runs...etc. There's little difference between the different animals, the process of aftercare is very similar.
Excess money can be used to buy paraphenalia for your house, vet certificates, etc. Horses can be exported to Pippa Funnell 2 via the DS wireless link, apparently, if you know someone with that title, but not to the Loctite factory. None of the animals can actually die (should be no tears), you can't raise the fees nor bill for unnecessary medication, so everything is at a very simple level.
It's all run of the mill, very average gaming for the younger gamer, but my daughter likes it (hence the 4 stars), and I liked the cover on the box.