Originally Posted by khuon
You left out one important word: can. There is no guarantee that spending more money will get you a better bike. The OP asked a very generic and ambiguous question. A generic answer is that a $5k bike can ride like crap or it can ride like the best bike ever made. But the same thing can be said of any bike at any pricepoint. The bike does not make the ride. The bike and the cyclist do. My point is that the price of a bike is not necessarily directly related to its ride quality.
Quite right & thanks for pointing out my omission.
You could put George Hincapie on my bike (since we are roughly the same build, give or take 55 pounds) and he likely would not care for the ride. It would be too stiff for his weight and have too high a position.
The best bike is the one you can afford and enjoy to ride.