If you've enjoyed Mortal Kombat in the past, this is a must get.
Pros: Carries on the MK tradition of being extremley bloody, awesome fatalities, good mixture of new and old characters, excellent graphics, stages look great, easy to pull off special moves, chess kombat and puzzle kombat add interesting side games, online play is smooth, very fun to play with a group of people.
Cons: Too much emphasis on Konquest mode, you should be able to unlock characters and stages through arcade mode as well. You don't get much for completing arcade mode, which is what Mortal Kombat is all about, instead you have to go through a mediocre Konquest mode to get new characters, Konquest mode gets annoying with all of the training you have to do.
Overall, if you enjoy fighting games or you're just a MK fan, this is a must get. While the Konquest mode can get tiring, it's worth it to unlock characters and stages.