The problem about Pokemon Mystery Dungeon is that you either like it or you don't, considering that both opinions can be as easily found in such threads. I think it depends on how particular you are about games. If your definition of a good game is something along the lines of Halo 3, where graphics, gameplay, game engines and the money pumped into its development are all on the high end (not to say that people who like Halo 3 don't like PMD, just using it as a bit of a contrast), it is unlikely that you would enjoy it. If you're a simpler gamer who can overlook some deficiencies to enjoy the storyline, interesting game concept and such, by all means go ahead.
On a slightly less related note, I am not keen on wearing out the DS touchscreen just yet.