No hate. Wikipedia has some fairly good write-ups on the topic.

http://en.wikipedia.org/wiki/CV_joints

What it boils down to is that U-joints are simpler and stronger but have 2 limitations:

1. The joint requires scheduled maintenance
2. The 'drive' shaft and the 'driven' shaft must be parallel or a vibration will be introduced.

CVs are more complex (expensive) and not as strong. Additionally, they also have a weak link ... the boot. As long as the boot remains intact, the CVs require no maintenance. The main benefits are:

1. The 'drive' shaft and the 'driven' shaft can be at any angle in relation to each other (that's why you find them on front wheel drive cars - the compound angles introduced by suspension travel and steering).
2. They operate smoothly so do not introduce any vibrations.