When this game came out, I do recall it having the best graphics of any game to date and was claimed by many to be an instant classic. This claim was rightfully made. This was the best platform game of its time and is, in my opinion, one of the greatest games of all time.
The two player tag team setup in this game was awesome and allowed you to play a game that would normally be a one player game with a friend. Unlike most platform games, both players were active at the same time and could switch places as the dominant character at any moment. This setup, in conjugation with taking advantage of Donkey's and Diddy's individual attributes in certain situations, gave this game its uniqueness and main source of strength.
This is one of the only games on the SNES where the graphics would still be considered fairly impressive even by today's standards. The world had never seen anything like it before and the visuals were truly breathtaking.
Only certain games in franchises such as Mario and Castlevania could possibly compete with this game in the "All Time Best Platform Game" category. I am not quite sure how many times I beat this game, but, I do remember enjoying it every time it was in and the red light was on...