It's a cute show, and it's good. The facts that I'm 22 years old and a show that seems to be aimed at the 8 & Under Club held my interest for more than a minute should attest to that.
I tuned in expecting a show about a world populated by hamsters and other animals alone, and I got a show about hamsters and their owners. Particularly the main hamster, Hamtaro, and his 10-year-old owner Laura. The general gist of the show is that Laura's family has moved to a new town, and her hamster Hamtaro, who's vastly smarter than she knows (she still thinks he can't get out of his cage, silly girl), makes all kinds of new friends.
The world of these hamsters is basically a mimic of the human world; hamsters seem to have the skills and personality quirks of their owners. And every episode, there's a situation that Laura faces that is duplicated in the hamsters' lives - Laura's dad loses his glasses, Hamtaro gets some of his friends to help look for them; Hamtaro follows Laura to school, and gets an idea for a hamster school; Laura gets a crush on a boy, a girl hamster has a crush on a boy hamster. So on and so forth.
In particular, the hamsters seem to view it as their mission to take care of their owners. Just listen to one of the lyrics in the theme song: "If she heads for trouble, we won't let her.: In one episode Hamtaro thinks he made Laura sick by keeping her up all night (she just needed a nap), and another hamster tells him: "Humans mean responsibility. If you can't take care of your human, you shouldn't have her."
Overall, if you're into cute, it's a cool show. I'd still rather have a show that's less about real life in the human aspect (I have to live real life every day, after all, I don't need to see it in cartoons), but this is okay.
Warning: any kid over 8 or 9 will probably be less into this show and more into one of the DB shows or shows of that nature.
