CVT transmissions are technologically amazing. The biggest perk to them is they can stay in the power band of the engine the whole time, and can switch from the power band to the fuel efficiency band, and stay there. They are most commonly used in snowmobiles.
With standard and automatic transmissions, every time you shift, the revs usually fall out of the power band of the motor, which wastes more fuel to get back up to the power band.
With a CVT transmission operating how it is designed to, they are constantly within the power band or the fuel efficiency band, depending on what the computer determines they should be in. This guarantees more power on demand.
Unfortunately, a lot of companies decided to forego this advantage because customers want to hear a gear shift. So they program the computer to act like the transmission is shifting. This causes excessive wear on the transmission, making it tend to break down faster. It is also what causes the "rubber band effect"