OK just checked and I can fill you in so here goes. This is just the stuff where I think it affects a C63 and not the changes to the other C class models
Styling
Chrome strip in exterior mirror changed to black
Chrome speaker surround changed to black for standard interior trims
Renaming of Agility Select to Dynamic Select
Interior lighting features now part of Premium Packages (Red warning lights in doors, illuminated cup holders, rear foot well lights). So these you used to get without Premium but no longer.
Air vents surround changes from silver to black
Driving Assistance package
This gets its own section as loads of changes here.
Distronic Plus becomes Distronic Plus with Steering Assist and Stop&Go Pilot
"DISTRONIC PLUS is a radar assisted cruise control which also maintains a safe distance from the vehicle ahead in all situations. Steering Assist tracks road markings and the path of the vehicle ahead to keep the vehicle on track."
Lane Keeping Assist becomes Active Lane Keeping Assist
"Detects signs of inadvertent drifting out of lane and warns the driver by vibrating the steering wheel and, if necessary, triggers one-sided braking intervention."
Blind Spot Assist becomes Active Blind Spot Assist
"A warning light in the exterior mirrors flashes if another vehicle is detected in the blind spot. Autonomously one sided braking attempts to prevent collisions whilst changing lanes despite another car is driving in the blind spot."
PRE-SAFE becomes PRE SAFE Plus
"Initiates occupant prevention measures if a rear-end collision is imminent, including activating the hazard lights, reversible belt tensioning, adjustment of passenger seat positions and closure of windows."
New PRE-SAFE Brake with pedestrian detection
"When the danger of a collision with another vehicle or a pedestrian is recognised, PRE-SAFE[emoji768] Brake gives the driver a visual and acoustic warning. If there is no reaction, the system can reduce the vehicle speed autonomously - right up to full emergency braking."
New BAS Plus
"If a critical situation is recognised and the driver applies the brakes, BAS PLUS can increase the brake pressure ideally preventing a collision."
New Option - Remote Online
Remote Online enabled the vechile for Connect Me remote & location services for 3 years
I could write about this but have a look in the App Store** as you can download the Connect Me app already to see what it will allow you to do. I believe this is a free option at least on our cars because I have it listed on my order as no cost.
If you have the 360 degree cameras you can even drive your car using an iPhone app so you can pull it out of a car parking space to pick you up near a store when it's raining!... OK I lied, this one isn't true
Other changes
Comand Online only available in Premium Pack, not separately.
Burmester sound only available in Premium Pack
Fineline dark brown wood becomes dark brown ash wood
And that's it. So nothing major unless you have Driving Assistance where it's been improved a lot. The Online features should be cool as to me it looks like it beats what BMW remote will do on my 3 series currently.
** Other phone models are available but only poor people don't buy iPhones so I assume if you can afford a C63 you have a real genuine Apple iPhone.
There probably is an Android app though...