The ships are a neat addition. I need another play or two to decide how much I like it. UPDATE (Mar. '14): It's a bit swingy, depending on if you draw one of the ships early enough, but bringing down a "ship hammer" on your opponent is pretty satisfying.
(Apr. 2011): It's hard to to know when to pick a leader, but I tried it a couple of times in my last game and I won, so I guess they aren't so bad! UPDATE (Aug. 2011): I don't bring it out when teaching, but whenever all the players have played before, there's no reason not to include it. I tend to buy a couple of leaders per game, and it seems to work out for me.