We had a Porta-bote years ago; there are pros and cons. It rows better than a flat bottom inflatable. It folds relatively flat, but there are seats and a transom that take up as much (or more) space as the boat, and you have to find room for those. I had a 12' model and was told it would plane with a 5hp motor; it didn't. It is virtually indestructible (won't get sliced up on rocks or oyster shells). It comes with a "pry bar" sorta thing to hold the boat open while you install the seats and transom (that's what gives the boat its shape)... if that slips while you are standing in the boat, it will close up on your legs. Yes, I experienced that. You need a space as long as the boat and wider than its beam to set it up. It doesn't pound over small waves like a solid dinghy or bounce like an inflatable... rather, it "slithers" over waves. A bit disconcerting at first, but it is a sound design.
The number one reason we sold it: the joint at the center of the boat is made out of a black rubbery material that leaves a skid mark on gelcoat that is darn hard to remove if you are dragging the PB onboard. We used ours with a sailing trimaran (Corsair) and there was plenty of room on the nets to set the PB up and stow it. You'd need a sizeable power-cruiser to have space to set it up onboard.