I got the game four days before its official street date. I've been playing it for about a half hour a day every day since then.
The gameplay in Nintendogs is a Tamagotchi with adorable 3D graphics, rudimentary touchscreen headtracking, and janky microphone support. The gameplay on a 1997-era Tamagotchi is more complex, actually, as they can age/die. Nintendogs just stay young puppies forever.
There are no "environments," beyond square, bounded rooms. There are no items that actually affect your dogs in anyway beyond short visual canned animation loops. There is nothing to "do" except feed/water/clean your dog, take it for a walk, and throw a frisbee / compete in "agility" dog show / compete in obedience dog show.
If I were reviewing the game on a 10 point scale, I'd give it at least an 8, maybe a 9. It's good, it's cute. But it's shallow. That's different from simple ... simple is good. Shallow means that, honestly, there's not that much to do in Nintendogs. The game has no meat.
It is a Tamagotchi with adorable 3D graphics, rudimentary touchscreen headtracking, and janky microphone support. And Famitsu has declared it a "perfect" game. A shallow puppy sim that, like a Tamagotchi, will likely wear out its welcome in a few weeks. That's why I'm in such disbelief.