In my purchase decision I compared the C300 Luxery model to the Lexus IS 250/350, BMW 135/335 and Saab 9-3. For all I was looking at '08 models. In my opinion, the Mercedes C300 offered the greatest driving performance and luxury experience along with the best value. Certainly the fun factor is greater in the BMW's, the Lexus is slightly quieter and the Saab most offordable. The C300 is, however, very fun to drive and the engineering allows you to push the 3.0L V6 to its limits. A very fun ride but with comfort for every day driving.
It's a Benz! The redesign is a great step up from previous models (ie - lack of American design influence is a huge plus). The options are reasonably priced comared to competition.
I purchased the luxury model because I loved the interior. I did upgrade the grille to the sport model grille since the luxury model is a bit boring looking for such a small sporty car. Other suggestions include: heated mirrors, DVD navigation isn't great compared to others I've seen (ie - Lexus).