Mega Man Anniversary Collection is weird. The buttons are switched, which in and of itself would not be a big deal, but with the horrible Gamecube controller and button design it can be frustrating.
But, MMA really makes the Mega Man game experience too easy (except for the Wily levels) because you can save after beating every boss. And I know there is password features for the NES games, but it is still password for some reason I found running through all the Mega Man's basic levels much easier in MMA than in the original NES games.
The series is fun though, but you do realize that after Mega Man 6, the series goes downhill fast...and I do believe it is because of the more advanced and detailed art style.