As for styling, the previous Impala was rather bland, but the new version is now in line with the current flashy Baroque fashion.
The side view tells most of the story. Front overhang is not quite as severe as was common in the 1990s nor is rear overhang as great as in the 1970s. The passenger compartment greenhouse is proportionally long, ending in a semi-fastback shape; this approach has been in vogue for nearly ten years. There is plenty of sheet metal sculpting, which is why I used the word "Baroque" above. This too is a styling fad.
The various folds and creases forming the sculptural side composition are professionally done in the sense that there is follow-through between separated elements. For example, the lower creases and indentations on either side of the rear wheel opening are continuations interrupted by a bulge around that opening. More subtle is the continuation of the crease near the top of the front fender. It begins with a fold aligned with top of the upper grille and headlamps and strengthens abaft of the bulge around the front wheel opening. It fades away at the rear door handle, but is picked up again where the rising crease on the rear door becomes horizontal. If these (approximately) horizontal elements had been offset rather than continuations, the result would have seemed comparatively cluttered and confusing, the work of an amateur stylist.
Just for fun, I include these images of a Chevrolet from around 40 years earlier that might have served as inspiration for the rear door and rear fender area curved sculpting on the new Impala. True, the shaping is different, but the slight suggestion of a rear fender on the Impala brought the '73 Monte Carlo to mind; can we call it a Retro touch?