It's pretty good. From what i remember, it's missing 3 characters; one of whom is Evil Ryu. At this point, Evil Ryu is exremely redundant as a character (although you could make that arguement for all the Shoryuken characters....)
In 3D Edition's defense, the four extra characters (Yun, Yang, Oni, and Evil Ryu) were part of an update that was made after the 3DS version came out. It's not as though they deliberately axed four characters to save space.
And yes, SSFIV is a very impressive port. Aside from the static backgrounds (which you'll be looking over anyway, since they're not the centre of the action), it is amazingly faithful to the home console versions. Hard to go wrong with it. --- R.I.P. fungivore, 2012-2012