Shahid Kapoor made a better debut than John Abraham. It took quite sometime for John to get hold of himself as an actor.
As far music goes, Ishq Visk is something not genuine but Jism's music was the haunting kind. It had a larger impact. So it's Jism all the way.
As for the movie goes, Ishq Vishk was your run-on-the-mill college love story which was entertaining due to the fresh faces. But Jism had much better content. As far the movie goes I don't rate both of them higher but I would pick Jism since Ishq Vishk has run it's validity.