Online Manual
http://game.capcom.com/manual/sfxtk/en/
This game seems to be a solid port, all the content is intact from the console version, the graphics look good (although slightly downgraded, though background have animations unlike UMvC3),and the gameplay is all intact with 60FPS. This is probably one of the best looking games on Vita with so much content.
Cross Compatible DLC
Comes with all the DLC characters from the console version for free. If you buy the Vita version you also get the DLC characters on PS3 version for free. Also all DLC is cross compatible between the Vita and PS3 version, so you only have to buy the DLC once. As a pre-order bonus many stores are offering Alternate costumes for free for the core cast (38 characters).
Cross compatible online play
Similar to WipeOut, SFxT offers cross compatible online play between both Vita and PS3 versions. For me personally this is the seller, with UMvC3 on Vita the online community was quite dead, however because this game will combine the PS3 and Vita community, hopefully the online commyunity is more active than UMvC3 was on Vita.
Vita exclusive features
-Augmented Reality, take pictures of your characters
-Front and Back Touch Screen support for shortcuts
-Ad-Hoc Fight Request for getting games from people nearby
-KO Monument (no idea what this is yet), something about collecting trophies from your defeated opponents
Free 2013 Patch Update coming
Apparently a big patch is coming that has many balance updates, hopefully Capcom address aa lot of the complaints coming from the hardcore tournament players. Here is a link to some of the balance changes that will happen in the update
http://shoryuken.com/2012/10/19/street-fighter-x-tekken-ver-2013-changelog-for-street-fighter-cast/
IGN Video walkthrough
http://www.youtube.com/watch?v=xO8lNtpWZho
Link to the OT for the console version
http://www.neogaf.com/forum/showthread.php?t=464822