Okay, after reading the above comments, I've been reminded of a few things and are going to expand my up/down list.
Up: Better graphics (I don't care what anybody else says), tons of modes and trophies and CDs and stickers and SSE and *passes out*
Down: Disappointing intro, abysmal voice acting, a few too many bland stages (Frigate Orpheon is pathetic), and a lot of the trophies for Wii games come across like ads (read the one for the Excite Truck trophy. That, and the excessive amount of nods to DK: Barrel Blast is just pitiful).