Mega Man X Collection will satisfy those who just want to play all the X-games again.
In the transition between the NES and the Super NES, the Mega Man gameplay evolved quite a bit. Mega Man X could climb walls, dash, and eventually do things like hovering in the air. It also eventually introduced another playable character, Zero. Although Zero had more of a mentor role in the first X game, by X4 he was a full-fledged playable character (technically the first game he was playable in was X3, but it was limited). The reason Zero was such a big gameplay addition was because, rather than shoot like Mega Man gameplay had always been, Zero prefered melee attacks with a lightsaber.
The X collection has 6 Mega Man X games. The biggest problem with the X Collection is hat some of the games weren't too great back when they came out. Don't misunderstand me, some of the games on this disc are just fantastic. The first two X games were great platformers. X3 and X4 were pretty good games, X5 is alright, but X6 is just a terrible game.
The quality of ports are better than the Mega Man Anniversary Collection, but they still have issues. A lot of the audio doesn't sound right. There are some occasional graphical issues, but for the most part they actually fixed problems with the games (the original SNES games often had some slow down problems).
There are just some weird things about this collection. They added in X saying "damn!" on the first level of Mega Man X1, but they didn't fix the translation errors in X6. They also removed the Japanese voices from X6 for some reason. Capcom also used the 32 bit version of X3 instead of the Super Nintendo version.
Also as an unlockable in this game, they have included the previously unreleased in the U.S. Mega Man Battle and Chase. It's kind of cool but the nostalgia wears off fast. The only other thing to unlock in this game is a gallery. It's disappointing that there is so little extra content in this collection considering how many extras there were in the Anniversary Collection.
Mega Man X fans should go and definitely pick this game up. Not too many other people will enjoy this collection though.