Does absolutely nothing new in an utterly boring fashion. Bottom-line, the most derivative of the series to date.
Let me just say right now that Mega Man 10 is probably the worst game in the original series. It's to the point where I managed to get all the way up to the last stage and had a hard time just bringing myself to finish it, which has never been an issue in any Mega Man game I've played up to this point.
Be warned, this review is going to have spoilers. But when you get right down to it, anyone familiar with the series can see the 'plot twist' coming from a mile away.
The entire game can be summed up with just one word: 'derivative'. Holy crap, this game is derivative in a series FULL of derivative games. This one's the most derivative of them all. Not a SINGLE element of the game cannot be traced back to a previous game. NOT A ONE. Playable Proto Man? Mega Man 9. Playable Bass? Mega Man and Bass. Challenge Mode? The PSP remake of Mega Man 1 entitled "Mega Man Powered Up" (Proto Man was also selectable in this game). I could go on.
What's even MORE frustrating is that it could have easily been less derivative. The story's concept got every Mega Man X fan excited. The Roboenza Virus could be a prototype Maverick Virus! Holy crap, the two series' are finally going to be linked! But no, Mega Man 10 takes away this dangling carrot in front of us by having Wily come out and say "LOL I made the virus and duped you so I could infect Mega Man, you losers. HEY LOOK I'M THE GAME'S ACTUAL BOSS FOR THE 11TH TIME IN A ROW! BOY I SURE FOOLED YOU DIDN'T I??"
The stage designs are gimmick-laden and uninteresting. The music is bland. The weapons are difficult to use. Playing as Proto Man doesn't change the game enough, and while the presentation makes it seem like you can, you can't switch between Mega Man and Proto Man during the game. This game does absolutely nothing new and doesn't try anything to help hold your interest. It's really sad. I just don't see how the creators of Mega Man 9 (and the excellent Zero series) could have made a game like this.
Unless you're an absolute die-hard fan of the previous games no matter how derivative they got, or a completist, do NOT play this game. You will miss NOTHING. While the gameplay that made Mega Man a hit is still there, there are SO MANY other Mega Man games out there that would provide a better experience to a newcomer. There's no need to cater to this bottom-scraping effort.