If you can go past the disgusting single player difficulty, these are still awesome.
What you get from this collection is simply the first three games ported to recent generation hardware and put together. We all know them well, all great games that might appear better in our nostalgic mind than what they really are today. As fighting games they're simple but effective; as single player game they're disastrous; as multiplayer online it's pretty cool, though not so hot as it used to be.
They play like they played in the old days, with MK1 being the simplest of the three, MK2 the most elegant and UMK3 being the most dynamic. They follow Mortal Kombat's formula of simplistic approach and insanely memorable scenarios and fighters. The snappy finishing moves that made the series famous are as kool as they used to be. Plus, every move from every character is shown in the moves screen from the pause menu, both specials and finishers. I remember the laborious days browsing magazines while attempting them and now things are much easier.
Playing multiplayer, online or local, is a blast. Especially if both players don't differ much in skill, the matchmaking tries to put together players with related skill-level so even playing strangers over the internet is shouldn't be too drastic a change. Though I believe most people who play this religiously aren't casual buyers, unfortunately. A curse every games that's not insanely popular has to endure.
Single player game is awful. As a port from the original arcades it simply lets you win the first two fights or so before the CPU enters god-mode and will absolutely destroy the human opponent guessing basically every move. Even with the difficulty set to very easy these games are painfully hard, unless you manage to come up with some nifty plan to overcome the destructive powerhouse that is the CPU you won't have much of a change, especially on Ultimate MK3.
There's not much else to be done except choose the game and play it. In the old days we used to have so much fun unlocking secrets on the start screen, now we don't even have one. At least they didn't port the bad version of Ultimate MK3 from the Super Nintendo where animalities were removed. The mercy move wasn't, so we spent hours upon hours trying make what was impossible come true, perform animalities. Since this is from the arcade version you can perform every finisher available on the version.
All in all it's pretty decent for people with good memories from these games but it lacks a punch that other compilations had with bonus features and game modes. It's a simple port that does nothing at al to solve old problems that seem to have grown bigger and worse during the years. It's worth a few bucks in a sale if you ask me.