Hmm, I gotta chime in here as a big Cervelo owner, retailer and believer.
The P3 is solid for a number of reasons in my opinion. It is aero (according to some tests and based on my expereince- which is utterly subjective), has oddly good ride characteristics including comfort and handling and, most importantly to me, is a bike where you can acheive a very high performance posture or position.
Additionally, our experience has been that the bike is mechanically very dependable. We have had absolutely zero frame failures of any kind. The dropouts work well, the frames are consistently in good alignment so the components work well, the aero seatpost clamp is entirely trouble free from our experience (unlike some others from other companies) and the head tube is a standard 1" steer tube, which I like for aero characteristics (that said, I like the Kuota with the massive 1&1/4" lower headset race and 1&1/8" upper race because it is so nice and stiff. Probably not too aero though).
I’m on my 2nd P3. I had a P3 that I set up in a kind of “Bjorn” like position. I didn’t care for that position quite predictably but it was a worthwhile fitting experiement. My 2nd P3 is a new P3SL I am building now. I like the matt black appearance. I’m not too concerned if whatever finish they put on it makes it lighter or faster. The original version was plenty fast enough for me.
It’s also worth pointing out that the P3 is one of very few bikes used stock by sponsored Tour de France teams in time trial stages. I know how that equipment game works, and that is quite a coup on Cervelo’s part. That is extremely unusual in the entire history of the Tour de France.
Mostly though, I ride a lot of very nice bikes often. I ride my own, which I change frequently, and I ride customer’s bikes going out the door. I also have to be responsible for the mechanical integrity of a bike that a customer is pinning their hopes for an important race on.
I know, based on our experience in our store and my own personal experience, that a Cervelo P3 is dependable. When I sell one I don’t worry.
From a business perspective, the staff at Cervelo are pleasant to work with. They are kind, courteous and professional. They have helped me build my business. They have consistently demonstrated commitment to us and honored that commitment when other vendors have, quite frankly, dicked us around. That also adds value to our relationship with Cervelo and my support of the brand.
To me, that is what the big deal about Cervelo is.