Here's an excerpt from the Road & Track review:

The four small circles on the back bumper of the new Mini Cooper Convertible are hardly noticeable, but they're important – they're the sensors for the car's Parking Distance Control. PDC on such a small car? Those who've driven the U.K.-built car see this beeping back-up warning system as tacit acknowledgement from BMW that the view out the back of its ragtop Mini is not especially good, top up or top down.

That, however, is about the only problem of substance with the new Mini Convertible. Otherwise, this car is what you'd expect: an excellent-handling front-driver with all the charm and economy of a regular Mini, plus the added fun of a high-quality soft-top that goes down at the touch of a button. All for $5000 more than a hardtop Mini, with a weight penalty of 220 lb.

You can read the entire article here.