Our C63 has been very reliable and a ton of fun. With snow tires, it has no problems in the bad weather either. Practicality isn't affected over a regular C as the seats still fold down and all the amenities and creature comforts are available. Issues have been minor - lightbulbs seem to burn out fast (not the HIDs) but the foglights, rear license plate bulbs, etc. The major expense is obviously fuel - not just premium but the 93 or 94 octane ideally as the engine can get grumpy with 91 octane. On the highway, you can get down to about 9L per 100kms but in the city, it can get close to 20. Rear tires will wear out twice as quickly as the fronts and the factory alignment settings are set up for handling so don't expect economy car tire life.
Handling is well above average and it's a superb highway cruiser/GT. If it were me, I'd add even wider tires and wheels - you can never have too much rubber on the road IMO. Power is superb - no matter how steep the hill, this car will take it with ease without feeling stressed. The noise the car makes is also really nice - you will scare people starting the car up and the rev-matched downshifts will get you lots of wonderful braps and gurgles. The automatic was changed to the Speedshift 7 speed in 2012 (along with the revised interior). Brakes are phenomenal and scrub speed easily though you do get a fair amount of brake dust.
