The CVT is really the perfect transmission, except for the fact they are weak. As in the lack of ability to carry a large amount of power.
Think about it... if you have a normal geared transmission, you are governed by those 4-5-6 etc pre-selected gear ratios.
When building a race car, gearing is very important. The ability to get the car moving quickly and keep the engine in the powerband, while reducing the total number of shifts is key.
What if you had a transmission that could gear itself for a launch (no need to slip the clutch), then regear itself for the 60', 1/8th, and 1/4mi times. You would be able to get the most out of the engines power curve. Oh yeah, and then regear itself to get 40mpg on the ride home...
The problem with thse transmissions is the way they are tuned. The First Calibers that had these were SOOOOOO slow and got rather poor fuel economy. They got better this year, but still aren't great. It's all about the tune... and getting those gear selections correct.
Nonetheless, the biggest issue is the in car noise... these cars with CVTs are loud and annoying...