Pretty much not for everyone.
Basically, you can look at your Pokemon and somehow interact with them (throw them around...). You can also see them interact with other Pokemon or with Miis.
The game can only connect with Pokemon Pearl and Diamond, which is a shame if we consider how a lot of people have Platinum and how Japan CAN connect the game with Platinum. Other than watching your pokemon, you get requests of what Pokemon to catch, and sometimes, Hayley(the "main character" of the game) will trade your Pokemon for hers, which are usually really good.
So yeah, that's basically it for the gameplay. Also, something to not is that Pokemon are file locked, meaning that the Pokemon you store in the ranch can only be transferred to your savefile. if you delete the game, they can't be recovered.
You can also visit your friends ranch (or sometimes a random ranch or AI's ranch) sometimes and take pictures.
Overall, not really bad, but just not very entertaining/rich.
6/10
Presentation: The Pokemon look cute in this game (if you've seen the images, you know what I mean) which is not a bad thing. The graphics are simple, but well done, and the Pokemon interactions are visually good.
The music, while really repetitive, is soothing and fills its purpose.
7/10
Story: The story is about Hayley, who wants to live with tons of Pokemon and fill the ranch. Not very deep.
6/10
Replay Value: There's a lot to keep you coming back, considering how the ranch can keep up to 1000 pokemon and how Hayley's requests are sort of fun to do.
8/10
Fun: This game was pretty fun to me. Doing the requests is interesting, even when it gets boring after a while. Other than that, I don't have much to comment about, since this is not a very interactive game and rather serves the purpose of soothing you with its music and cute graphics.
8/10
Overall: Not really a good, game, but Pokemon fans might want to check it out as a storage device or to get special Pokemon (Mew and Phione included). If you don't have the DS games though, there's not much to do other than seeing the Pokemon so you should skip it in that case.