It's more forgiving than those NES games of times past. I suck at Mario, Megaman (etc), but I adapted to this game fairly quickly to the point where I can have fun with it. The difficulty really spikes when you're trying to get certain of the Feats in the game, especially the one that involves not spending any money (which means no upgrades... so you're basically nerfing yourself and trying to survive intact).
Definitely give it a go. It's a very smooth, pleasant experience that hones your ability before you get to anything even approaching hard in the game.