I downloaded Mortal Kombat Arcade Kollection which contains Mortal Kombat, Mortal Kombat II and Ultimate Mortal Kombat 3, it's a really great package for just 800MS Points which is a bonus considering that once you could only buy Ultimate Mortal Kombat 3 for the same price, the emulation has some problems though.
Mortal Kombat works fine apart from graphical glitches and missing music on Goros Lair.
Ultimate Mortal Kombat 3 has the problem of not letting you enter kombat kodes on the VS screen, I know why this happens and I could explain why but I just really cannot be bothered.
Mortal Kombat II has the most problems though, there are plenty of graphical and sound glitches and sometimes even the frame rate messes up.
Sadly the online for all of these games is where is truely goes wrong. This is one of
THE worst games I have ever played online, konnecting (sorry) to a game is already a difficult enough task, the next problem is that all of the games lag badly! I have played with people who have a good internet connection and still the games lag terribly, it's not even the case of the games running slower, I find myself being unable to actually complete combos for my characters because my button presses are too fast for the slowly running game to register. I find this problem very strange because Ultimate Mortal Kombat 3 (released on XBLA back in 2006 I believe) never had these problems online so I'm confused as to why it is suddenly plagued with these issues now, the online play was also better in the first release of UMK3 because you could have up to 4 players in a lobby, 2 players would fight, and 2 would spectate and the winner would play the next game whilst the loser would be put at the back of the line and had to wait for their turn, sadly when Midway went under all Midway games were removed from XBLA and the servers were shut down
So if you are looking to play all 3 games offline then it's great, but I really cannot recomend the online part of this package though a patch has been anounced.