Mega Man 7 has some problems. I think the biggest one is Mega Man himself - he's too big (a lot of games at this time had a problem with making the characters too big to give them more detail), which means the room you have to maneuver and for the developers to put stuff shrinks. His pellets also move too slow for my tastes. It just kind of feels awkward. Besides that, 7's boss fights are some of the worst jokes in the series, up until Wily where there's a sudden brutal difficulty wall, and I don't like most of 7's music much, aside from the first couple of Wily stages. 7 also has some of the all time most worthless weapons in the series.
The best thing about 7 is that there are a lot of secrets and easter eggs hidden around. I appreciate that part about it.