My review is with reference to the 318i M Sport that I also rented for a recent overseas trip. I had the C180 in Avantgarde trim for 6 days. It came with 9G tronic.
For whatever reason, the suspension was awful. It transmits everything on the road into the cabin, and has poor absorption of the bumps. The car does ok for low-speed bumps but it thumps uncomfortably on high-speed bumps. Road noise is also a big problem at speeds above 80km/h. The car was fitted with Bridgestone Turanza T001 run-flats and they are meant to be comfort tyres. Super noisy. The 318i M-Sport that i drove before the C180, came with 18" Wheels and was quieter and more comfortable than the C180. Shocking. The 9G-Tronic gearbox wasn't smooth at all. It shifts hardly into gears quite often, unlike the smooth gearbox in the 318i.
The C-Class has an off-set steering wheel, and the seats were very uncomfortable for long drives, lacking in lumber and thigh support. Poor ride, poor handling, poor refinement... In comparison to the 318i M-Sport. And you thought those should be all the negatives? Nope. The cabin may be nice, with nice choices of materials for the switches. But the gloss black center stack scratches easily and feels absolutely cheap. There was a constant rattling near the driver's side A-pillars even though there was only 20,000km on the car. The 3-series felt better built with better fit-and-finish. The boot has a wider opening than the 3-series so it is easier to fit your luggage through the opening.
The C Class is supposed to be the most comfort-oriented car in the Compact Executive class, and it's premium pricing vs the rest raises expectations. I am putting this car right at the bottom of the class.

Good representation of Mercedes class design, both exterior and interior. Details are just exquisite.
C180 similar to BMW 318 and A4 in terms of engine size to looks. Merely sufficient. C200 would be just nice.
Smooth 9 gears transmission and only one with passenger memory seat in its class.

Overall nice styling externally and internally although I must say that just like BMW, Merc's styling is getting a bit dated and need a desperate refreshing change.
As mentioned below, the RWD idea is not crucial IMO as the speed at which the roads here can cater to will hardly make much difference between RWD vs. FWD.

My friend bought one and had the chance to sit in to experience. Went to view one C200 AMG at PI. Somehow different feel and different experience. Generally was impressed with PI C200 AMG with lots of features e.G. Heater seats & auto thigh extension for front seaters. C250 AMG bought by friend on the other hand was fully of complaints. Intrusive noise, bad customer service from authorized dealer, delivered different spec as showroom (with sports stitches vs without stitches), yaya papaya sale rep etc. In the end my friend had to fork out own money to do up extra noise insulation for 4 doors and ended up with minor scratches in the process of installation.
To be fair I did not test drive this car but mandatory fields must be filled in so I rated "Average" For handling and engine performance.

Drove my mum's car a few times. Felt that it is very comfortable and looks good. But at 190k, there are much better options available outside. First thing is when you spent so much money on a car, it should be at least German made not SA. The car was sent in a few times to adjust the brakes, suspension and Ecu that speaks about about the fitting quality of the SA. Engine don't feel as if it's 180bhp more like 122bhp, my sis 6 year old civic has a livelier engine.

Test drove the C180 in Feb. Have to say I really like the exterior styling. Its aggressive yet modern looking.
Very surprised to hear that the C180 does not come with genuine leather interior as standard. Also the steering wheel is manually adjusted. Huh? I thought this was a luxury car?
Anyway, start the engine and drove off. Hey completely different feel. Car is responsive. Acceleration is nice and smooth. Step down and the turbo engages smoothly bringing you rapidly to above 100kph. Nice body setup, next to no body roll when we took a roundabout exit from the expressway at speed.
Engine is smooth but not exciting.
Super Comfortable. My wife in the rear seats mentioned she had really good legroom and really liked it.
Tech comes standard too. Adaptive braking, auto dimmin mirrors.
BUt its so popular, there's a 6 month waiting period.....
Oh well.....

Was actually test drove on behalf of a friend who's keen on C200 (2.0L) but was told by SE that the C180 (1.6L) actually delivers 156bhp, approximately 30bhp lower than C200.
Exterior looks similar to the S Class with the LED lights and the curves that the S Class gives but at a much fraction of a price and much shorter too.
The exterior shape is a looker, plus with the standard 17 inches rims too.
Interior was sporty and Mercedes has done a great job re-inventing this C class to capture the young and mid executive hearts than the predecessor model.
The LCD screen and the controls use are a breeze where many options you can do with. And not forgetting its spiky shaped air con vents, looking like jet turbines to blow your mind away.
Seats are ok but is only C200 comes with full electric and memory seats with an additional of high price tag whereas the C180 comes with "Semi automatic" Electric seats, only the forward and backward is by lever and no memory options.
Sitting at the back is also comfortable and great back protection as the curves are reclined to your backs, same for front seats too.
GUESS WHAT ? This new C class comes with electric tailgate even for C180 as standard which is great.
Mercedes removed the traditional smaller classes gear shift knob and replaces with lever gear shift like its S Class....GREAT and feels you are driving their S class which its known as a BABY S CLASS to many.
The drive was excellent and when move off from junction to main road was easy as all you need is "Tap" On the gas and it GOES....
Mercedes also retains its HOLD or many known as START/STOP function in this version too.
When I tried revving and overtaking, its certainly a breeze with no lag and cornering was easy too without much body roll.
Perhaps, with adding options like the Drive Assistance Package and Intelligent LED lights should be more than sufficient to have in this C Class. Other options, its up to your pocket.
Driving this 3-point star (like a smaller S Class) will keep eyes turning back and is certainly a good choice for young to mid executives to get or in their choice list.
Great Job Mercedes.

It is indeed a very well balance and well built car. When I test drove it , it has A great balanced of comfort, handling/sporty and luxury. Plus a well known brand. The only downside is that it feels a bit clamped at the cockpit against the other competitors in the same class and as I understand the seats are not real leather.
However, it was one of my top consideration if not for the huge premium/margin of 40K ++ that C&C is creaming off due to the brand they have helped built. In other countries, the price difference is less that 3K to 5K against its competitors.