First off, being a huge Mega Man fan; I applaud you for how well it is. Since I grew up playing the series, I should know how the standards work and understand you have to give the game "some" difficulty.
But that being said, there are things that I really think you should adjust. First off, the drop rate for items is way too few. There is one Mini-Boss that requires me to use a specific weapon just to stand a remote chance of beating it. Sadly I lost because of instant ko on that stage. Next, is the knockback factor on some attacks. Even in Mega Man games there wasn't that huge a knockback. Another situation requires you to jump off timebombs, but (at least it makes me believe) you don't jump as high, thus falling to your death. Finally, that one problem everyone faces where once you reach one checkpoint you are forced to lose a life due to a glitch in placement.
Still, this game has me hooked, and it would be wrong to give you a rating that doesn't show that you have worked hard on it. So good job.