I went for a quick 60 mile run to see what it felt like, and it is preferable to the standard seat. It is more contoured and seems to fit better, also, the shape makes it easier to slide over a little to get a foot down. Being short of leg (29") this is really useful.
As to comfort on a longer ride, have to wait for the weekend. I found the original seat ok for 100 miles.
I've heard a lot about how the stock seat isn't quite up to par, but I'm up to 5,000 miles on my fizz now and i have absolutely no complaints about the stock seat.
I am 5ft 6" and 150 lbs. I found the stock seat ok, but after 100miles it was a bit hard on my poor ol' backside! Though I have done 200miles in a day, and then other aches and pains take my mind off it...
It does have a much better shape though. Feels more natural. Though, I dare say it would be easy enough to shape the original for much the same effect and save the money. But, it wasn't too expensive for a seat - 260 euros.
I'm getting by fairly well on the stock seat with a $40 pro-pad. 175 miles is the longest I've gone on it though. The first hour is fine, and from then on it seemed like a "uniform" level of discomfort that didn't get any worse for the last 5 hours of the ride.