My wife and I climbed Jack last year at the end of July via the Jerry Lakes approach. From the lakes, we crossed the intervening ridge, and got to Jack proper. From there we simply traversed about two thirds of the way across the snow slope (below and around a buttress) until we found a pretty simple (3rd-4th) way through the rocks. As I recall, we only belayed one short rock pitch around an exposed bulge. Above there it was some steepish snow, some easy rock, then the summit ridge and the summit. Only 2-4 parties a year sign in. We reversed the route for the descent, there was plenty of snow to down climb.
We found it to be a nice climb with interesting but not too demanding route finding. It appeared to me, from seeing rap slings and dead ends, that some people begin the ascent of the face too soon during the traverse; that leads to downsloping, slabby rock. I recommend the peak and route, it was a fun, rewarding climb.