Good game, but not as based as the first one.
The gameplay is pretty much the same, but they made dash available from the start, which is good.
Mavericks' levels are more challenging then ones from the first game, but I think that they were worse in design. Crystal Snail stage was grate, but for example Bubble Crab's was shit.
Bosses are more balanced, no Spark Mandrill this time, though some of them are still too hard to beat without exploiting their weakness. Wheel Gator fight felt more like a set piece, then a proper battle. And while X Hunters are a good addition, they make the game more repetitive, since now you have to return to the same level more times without even fighting Maverick. Oh, and animal (and I guess plant now) selection fucking sucks. Who though what after mammoth and eagle anyone wanted to fight a Sponge? Like, bro, the fuck is this shit? Also I feel like the designers put to much emphasis on insects and sea life.
Music is good, but it doesn't slap as much as the first game did.
Upgrades were pretty fun to use, especially air dash that you get from legs part, but Chest part's placement is so stupid, that I can't imagine someone getting it on purpose without guide.
In conclusion Mega Man X2 is just Mega Man X, but worse.