We replaced our Alfa 159 V6 Q4 Auto Lusso with the Mercedes C Class 350 CDI Sport March 22 this year. The GTi arrived the same day.
The Alfa never went wrong even once but it's fuel consumption was dreadful. It was just as well made as a premium German make. However, the Mercedes is a far superior car and is perfectly made. Completely faultless unlike the GTi.
I've never liked Mercs at all, but i'm really starting to like the new ones. The C-Class Sport you have there am1w looks brilliant, as does the new E-Class (even though i think the alloys look too small in the arches), the E-Coupe and the SLS - Amazing looking machines!
However, I am a BMW man and i think i would still have a 335d - amazing engine! Just a shame they still insist on using those awful run-flats!
Im glad Alfa have ditched the GM engines and hope they can restore some of the soul as listed below:
I would just like to stress that when the alfa turned up as a courtesy car i was over the moon. Looked great, very nice inside!
However after just a few days after driving it i noticed the following...]
Electric windows would go all the way down but stick half way
Electric window buttons were soooo stiff i had to use two fingers
Wipers didnt clean all of the screen
2.GTD had the most shocking economy 22mpg... on a diesel??? whats the point!
put a can in the drinks holder and you can no longer operate the stereo 
very poor visibility out of the rear of the GT
boot would never open automatically.. you have to get your nails under the gap to open it.
window/side mirror switches are located so far back you have to pull over and get out to use them
awful quality of buttons
using the air con is a joke... i could fart a less tempramental climate
so yes they look good.... but at a price 
^^^ Passion and soul displayed perfectly! After 3 months you would be smitten!