Mega Man was the first in an amazing series.
First off, I'd like to say, yes, the Rockmonster is pretty hard, but not impossible. Just learn his pattern and only jump over the blocks that either shoot at your legs or at your face and you'll be fine. There is a set near the end that you'll have to jump over two in one jump. Just learn the pattern, it's EXACTLY the same EVERY SINGE time. Now that I've learned it, I can sometimes beat him without even getting hit.
If you can't, just shoot him in the eye with Elecman's weapon and keep pressing the select button. It's a glitch and will hit him several times with one shot.
Other than that, this game will probably take about an hour or two to beat, but is an excellent time all the way through. Props to Capcom for almost getting their Mega Man series perfected on the first try.