it has a simple charm to it, your pokemon taking on a sort of Mii form of their own, interacting based on every possible variable, from race, to type, to nature, to the very concentration of those specific variables and your grand total. Taking snapshots is a refreshing way to spend time, and hte game actually rewards you with little skits if you have the right pokemon in there. (All the unowns will line up to mimic a keyboard if you have them).
Admittedly though the actual interactiveness is very limited to speak of, other than visiting other people's ranches just so they can show off their pictures and pokemon. The pokemon skits don't happen immediately and are completely random, and you may not find it worth your time to wait for them.
However, it IS the only way to legitimately get a Mew, and you can get a phione from Hayley that is technically an event pokemon. not to mention all the other pokemon she trades you as well, which really aren't all that bad. At base, it is a supplement to D/P. If for no other reason you should get it for the pokemon you get out of it. I personally found it to be a quaint little game that provides little nuggets of fun and amusement, but it most certainly isn't anything I would play at length.
