I own a cervelo.
Its a good bike. I mean, its fast, very stiff etc and probably well engineered. However, there is a lot of hype around cervelo. I can honestly say it wasnt worth the coin i dropped on it vs a giant or merida for example.
I happen to have worked at a Cervelo dealer.
Their customer service isnt really that bad, but their build quality is.
The frame I bought didnt have an excellent finish quality. Just little things like slightly poorly placed decals or paint cracking near the cable stops were enough to make me unhappy. It also has a lot of problems with the design of the cable stops causing a decent bit of cable friction.
My observations about my S2 would be that it is a decent bike. I can just notice the aerodynamic benefits (just), its stiff and reasonably light. It has some really stupid geometry though. Its not a great descender due to its TT length chain stays and has a really tall head tube (not great for a flexible racer, but probably good for a triathlete).
All in all, ok bikes, but really not what they are hyped up to be, a bit like apple products.