I agree that it moves rather slowly, but I actually rather like that, as it gives me time to really get into the adventure. What annoys me, in no particular order:
1) No Fire-types. Infernape is righteous and Rapidash is OK, but they are the only two Fire types in the whole Sinnoh Dex! Where are Pokemon like Ninetails and Camerupt? Did they just not fit in with Sinnoh? I know you can teach other Pokemon Fire moves, but I like my Fire moves to have STAB.
2) Team Galactic's costumes. These guys get a storyline that's almost a cool as the Aqua/Magma storyline, and they certainly fight better than Team Rocket ever did. Why are their outfits so goofy?
3)Too. Many. LEGENDARIES. Seriously, we've gone from having just 5 in Gen I to 14 in Gen IV! I know that the legendary percentage has only changed + 2 % for the National Dex, but for the Sinnoh Dex, it's disproportionate. the Kanto Dex has 151, and 5 of those are Legendary. That's roughly 3% (1/30). The Sinnoh Dex has the same total, but 14 Legendaries, roughly 10% (1/10). When one in ten Pokemon is "one of a kind", just how legendary can it be?! This does not compute.
Other than that, though, D/P just may be one of the coolest games to come out in a long time. ;492;