Sut-The main thing that kills the game is the awful controls, specifically the grappling hook, getting it to work right when you want it to is a huge pain in the ass, the wall jump is also akward.
Another bad Gameboy game is Terminator 2, quite possible the single most difficult Gameboy game of all time-if you die just ONCE you have to start all over from the beginning, that alone is bad enough, but the stages are cryptic and frustrating as hell- In the first stage you have to get past an electrical barrier by shooting down towers in a very specific order that you'll likely never figure out without a lot of trial and error or a walkthrough. Then in Skynet there's tons of bombs on the floor which are almost impossible to jump over without hitting them due to the low ceiling, there's also a puzzle section where you have to reprogram the Terminator within a time limit, you can't pause to look at the puzzle as it just goes to a blank screen, so you just have to get insanely lucky(though you do at least get two chances this time), and the game only gets harder from there.