I finally got to check out the Japanese rom of Super Mario Advance 4. Some of the bigger changes is that theres 3 save files, and one that takes you to World E+ (E-reader world) Too bad you cant scan cards...
Theres just graphical enhancements and not much else. It does share some similarities with Donkey Kong Country though. The R button acts as a B button as well, and you have the ability to select 2 player mode (AKA Mario and Luigi), which is just a hot seat function as well. Great for Game Boy Player stuff. Too bad that theres no Mario Bros VS. mode within SMB3 (But Mario Bros. is included remember) Oh, so far all I can tell is that Luigi doesnt flutter like he does in the other Advance titles. He still moves his feet fast but thats it.
On the map is the L and R buttons, L brings up your item thing, it now shows 4 rows of items. R brings up a 2 choice menu, but all it does is take you to something about the E reader.