I've ridden my mates. It's a lovely bike, weighs next to nowt and is a real crowd puller. Would I buy one?.....No. Its a lovely bike but it cost my mate 5K and nearly cost him his marriage. My Raleigh Carbon Comp is 4 lbs heavier but cost £1100 in the sales. It rides almost as well and is certainly more comfortable over distance.
The one thing that I really hate about his S Works though is the horrible racket that the freehub makes when he is coasting. Honestly you can hear him coming from miles away. I'm not sure what wheels are on it but they are 50mm carbon clinchers.
If you decide to buy one then be prepared to feel cheated. My mate would never admit it but I know that looks at mine and wonders why he forked out the extra £3900.