not having active slings is not an issue for Jacks Open/Lucky Hand but i'd think it was a detraction if i never played it. i have a lucky hand and the lack of active slings is a good thing in this case. the ball still bounces just fine off the dead slings and since skill shots are the heart of this game, having the ball land relatively frequently on the flippers, helps. i also enjoy the chimes when the ball hits the 1110 point side lanes because the result is a nice 3 tone sound.
as Vic said, it's wise to only score three of the top 4 rollovers for max points but if all are hit, then the red light alternates beneath all 4 rollovers with every pop bumper hit for a WOW (Lucky Hand).
another cool feature is having all 9 targets reset when A-10 are hit and then seeing the 4 black targets drop leaving only the reds up. lots of great features and rules on this game.
my top 5 list is
Dimension
Diamond Jack
Lucky Hand
Capt Card
Expressway

Nice! I had a Mini Pool at one time and now it belongs with the other pins that I regret getting rid of. I'd love to get another one day or a Target Pool.