Good question about my Easy Seat, it does take a bit of getting used to. It moves as you pedal and you're not mounted on the bike as much as you're dancing with it-- that was my early impression, but after 10+ years on it I'll never ride anything else. But you can't take you hands off the handlebar.
This seat was recommended by my doctor after I encountered an injury due to a slightly nose-up conventional saddle. This is probably TMI, but if you want to read about it I have a page dedicated to this seat at:
http://www.thirdwave-websites.com/bike/easy-seat.cfm
I'm a bit of an evangalist for this seat- I think all the people with bikes unused in the garage because the seats weren't fun should try one of these. They cost around $25. I put 2000 miles a year on mine.
Cheers, Ed