Here's my say on the remakes. These are just my opinion:
Super Mario Advance: I actually loved the remakes. They added much stuff, plus voices, which made the game sound more lively and funny. Besides, they also give me a chance to play the classic games, but that's the point of remakes, isn't it? I liked all of the Super Mario Advance games I played.
Donkey Kong Country GBA: I never played the original, nor the remakes. I have no say in this :P
Super Mario 64 DS: I enjoyed the game and I liked it even more than Super Mario 64, though mainly the reasons is that is easier and Luigi is playable. I love playing as different characters, too, though it may annoy others. My opinion: very similar to the original, but way more stuff added.
Diddy Kong Racing DS: I didn't like the voices in the game, nor how you do the boost at the beginning of the ace, nor the balloon touch challenge (though they are better than Silver Coins, in terms of difficulty). The upgrades to the kart are nice, and same thing with the unlockables (though I mainly use Pipsy). The new courses are all right. I didn't like it how they replaced Pirate Lagoon's music.
All of them I played are great, but the lesser of the greats goes to Diddy Kong Racing DS to me.