There is no denying similarities to the W222 S-class rear design. Actually, they rear lights look practically identical which is somewhat of an odd decision by Mercedes to blen the S and C class rears so closely. Regardless, the design works incredibly well and the rear of the car is beautiful.
The front light design takes cues from E-Class so it would seem Mercedes blended the two designs together. The danger here is that the cars in the lineup may start to look too similar to one another. This is a problem Audi has struggled with as of late.
Hopefully Mercedes reveals the car officially soon. It is shaping up quite well.