I really loved Donkey Kong 64 back in the day. The game was absolutely massive, with tons of great levels and fantastic music.
However, the game has aged very poorly for the simple fact that switching between the five characters requires going to specific points in the level.
This should absolutely be corrected, as it is such a frustrating design that it overshadows the rest of the game. The remaster should let the player switch at will between the characters at the press of a button. I think this alone would go a long way into making the game a lot more fun.