LIKE:
-- The deep paper-rock-scissors strategy "hidden" in a seemingly kiddie game.
-- Large, spacious cities. Lots to do on the side.
-- Expanding Pokedex features and other available add-ons (like the watch that even responded to external input on the GameBoy / Nintendo DS).
DISLIKE:
-- While this is more in tune with traditional RPGs, I didn't like that battles didn't have more direct control from the player. In other more action-oriented RGPs (ie: Super Mario RPG), you have additional player-input that can affect the outcome of the match. This requires more skill from the player, which I like.
-- "Incomplete" towns or cities. More people than there are homes for or towns that just don't make a lot of sense in their planning...even for "small communities".