It is a port, but they are spending the time needed to make the controls good and playable.
Yes they have added Wiimote controls, but they also have support for both classic and gamecube controllers.
And Guilty Gear is one of the best 2D fighting series in really pushing the envelope of new fighting techniques and such. (I am sure there is a Japanese Exclusive game that is better, but not a World Wide Release game.)
Everyone should buy this game so that developers know Wii can support fighters.