I have owned/ridden both. They are both great bikes...but the VFR is hands down the winner in every category you can think of except price. It handles better, feels considerably more stable in the straights and corners. Carves the curves exceptionally better than the Katana. Lastly it has alot of aftermarket support...which the Katana is unfortunately lacking in.
Having said all that..i will again reiterate that both are great bikes and if you are tight on cash...then I would recommend the Katana..however if cashflow isn't a problem, then by all means, go with the VFR. You will not be disappointed either way.
To find out more info on the katanas...check this site out
Katana Planet