I have many memories associated with this game ever since I was a kid. My dad bought me this game when I was around 5 years old so I wouldn't feel like I didn't get anything from the mall when my sister got her ears pierced for the first time. My little self was aghast when I beat the fourth level. I thought that I beat the entire game, but instead it almost completely transformed into an entirely new game! For those of you who don't know about DK '94, the first 4 levels are pretty much the same as the original arcade game, but after you get past them, a totally new gameplay is introduced where you have to find a key and unlock a door while solving puzzles in order to advance to the next level. There are about 100 of them in total. Because it had so many levels, it took me five years beat the game as a kid, and the game never fell short of entertaining me.
This was probably the very first Mario game I ever played, and it set some pretty high expectations for me since it was such a great game. Upon playing the first Super Mario Bros. game, I was like, "Meh, this is kinda disappointing." I felt the same way towards every other Mario game since then (with the exception of Super Mario 3 for the NES). Even some of the newest Mario titles released on the Wii, did not even come close in enjoyment compared to DK '94.
I think the reason why I liked Donkey Kong '94 so much is because it really isn't a traditional button-mashing-platformer like 90% of the Mario games out there. While DK '94 still technically is a platformer, half the gameplay is focused on solving puzzles. This game requires you to be both quick with your thumbs and quick with your cranium.
There is nothing negative to say about this game at all. The guys at Nintendo did a fantastic job with this game, and any Gameboy enthusiast MUST play this game.
Here is a video of someone doing a longplay of the game: