I first played this through the X collection on Gamecube, and even though it's not horrible it really disappointed me.
Beside a minor upgrade in graphics, the only thing X4 does that first three didn't were cut-scenes. Very boring cut-scenes that I always skipped.
Zero was a lot better to play as this time around, but I just thought the levels were either too poorly designed or too plain difficult to play through. More hardcore MegaMan fans might like it better than I did.