Ok, I've used them and I have enough of an I.Q. to formulate an actual intelligent, cohesive sentence that describes my feelings about step-ins. They're gay...no wait, that's not what I meant. I honestly didn't care for them. Maybe it was a mental thing. I felt like I wasn't really strapped in. Not to mention my boots weren't stiff enough to make up for the feeling real bindings give me. I felt really loosey goosey going down the slopes. I had a heck of a time on hard turns.
On the positive side, they were very convenient. I could even step right into them off the lift instead of riding with a foot on the stomp pads.
Still, I didn't care for them simply because of the way they performed. I snowboard with my fiance and not a group of friends. She skis so she usually has to wait on me to strap in. It was nice to go right off the lift, but I just didn't have as much fun during the ride.
It's completely personal preference, though. You'll have to try both to really figure it out.