I always figure a good start point is 50% of list for secondhand. List price for the bike was £1600, so £750 is good on that basis. However, they were on Sale at Evans last year for £999, which is what I paid for mine. I saw one go on ebay last October for over £800 so £750 is again a good price on that basis. Obviously you don't get the lifetime frame warranty but these are road bikes, not mtbs, and that's the case with all pre-owned stuff.
As to the bike itself, very comfortable if the geometry's right for you. I have a 32" inseam and am only 5' 8", ie longish torso, and the 55" fits me perfectly. At least as perfectly as allows me to do 100 miles in the Welsh Hills, or anywhere else and only have tired legs at the end of the day, no aches/pains anywhere else. Weight wise it's about 18.7 lbs stock, so a bit heavier than some of the lighter steeds in our peloton, but then I'm only 10 stone so not an issue. Ultegra gears, STIs, Bonty Race wheels and chainset - mine's a triple - and Bonty saddle/bars/post/stem. Saddles are personal, some like the Bonty, I don't and swapped it. The frame is same as the (slightly) higher spec Zurich and slightly lower Versailles and combines the springiness of steel with the road buzz removal of carbon. Overall spec is very good, and the final clincher for me was the standard headset, S3 Cane Creek. I don't like integrated ones and will swap it for a King once it wears out.
I've had mine since May and am very pleased with it. Gets up hills nicely and on descents it's only my lack of bottle slowing me down. There are good reviews on
http://www.roadbikereview.com, but check the Zurich also as essentially its the same bike.
Also
http://www.lemondbikes.com