If you liked Deception, you'll like Unchained. A great portable fighter.
The added characters are: Frost, Jax, Kitana, Blaze, Goro, and Shao Kahn. The unfortunate part is that only two of the characters have the full roster of ending moves... 2 fatalities and 1 hara kiri. Those are Goro and Kahn. Now... the other added characters... Frost, Jax, and Kitana have only one fatality and no hara kiri and it's the same fatality from Deadly Alliance that they had. Blaze has no finishers. :(
With that being said though, I'm increadibly happy that they added Frost. She was one of my favorite characters in Deadly Alliance. Why?! Because she was hot and like Sub Zero (my fav character). The gameplay is all there including konquest, chess and puzzle kombat (I love chess kombat). The fighting is spot on as well and the graphics havn't taken much of a hit. IMO, MK Deception was the best of the newer MK games including Armageddon due to the fatality system being in tact. With the added characters, I honestly think that MK Unchained is the best of this generation of Mortal Kombat games. My only issue with it is a couple of the controls. Due to the PSP lacking an L2 and R2 button there are some alterations. First, to grab... you must press Tri and Cir at the same time. The grab weapon button is the select button on the PSP... which is almost out of range when in the heat of battle. Other than that though, MK Unchained is awesome and if you have a PSP.
I highly recommend it.