Megaman X5 is one of the best 2D side scrollers out there, and is also the best game in the series.
The good points about the game are there are different weapons, which are cool to have, as well as 4 different armour sets for X (and a unlockable Black Suit for Zero) and different scenes. One sees you fail your attempt to destroy the main hub thats spreading the Sigma Virus, and sees Zero being corrupted with it's power. Another one sees Zero suceed, but very weak.
The only bad point about this game is that the bosses aren't replayable, which is a big shame. Also some of the later bosses seem impossible to do without getting hit once.
Megaman X5 is a outstanding game, and anyone knew to it can quickly understand it.