This game and I have a little bit of history. Up until 2012 Star Wars held the accolade of being the only NES title I had ever played, and that was briefly in a long-forgotten computer shop in Derby about where M&S currently stands. Or is it Debenhams? The game also kept me company when my brother borrowed it for his Game Boy and ... I was hopeless at it. Back then it was by far one of the hardest console games around. It had slightly slippery controls, the annoying NES "bounce back" (i.e. involuntary leaping backwards when hit/touched by an enemy - a feature of many 8-bit Nintendo games), enemies with annoying attack patterns, and weapons that were distinctly underpowered.
The Master System port, gameplay-wise, is virtually identical to its Nintendo counterparts. The same "challenging" mechanics are present, except the graphics are spruced up and the soundtrack has received a decent makeover. For a system not known for its audio acrobatics, the programmers did a good job of wringing top tuneage out of the MS's weedy sound chip. And yes, it's bloody, bloody hard. It's one of them you would have needed weeks of spare time and infinite patience to get through 20-odd years ago - thank goodness for save states and walkthroughs.
Overall, there's a good game here if you're prepared to take it on its own terms. Not a timeless classic, but a worthwhile spin.