Well, on the surface, it sucks. Mercedes couldn't stomach Chrysler. The pentastar's curent dance partner, Fiat, makes some very beautiful cars, and has been extremely successful in turning itself around as a company, it doesn't exactly have a legacy of reliability, nor any real experience judging the American market very well, and Chrysler's bread and butter is still minivans and trucks...and of course its holy grail, Jeep.
Toss in VW? A company with pretty much two exciting cars in North America (GTI and R, both off the same platform), a recent history of Dieselgate shenanigans, and its own troubled experiences with reliability, market choices, and identity issues (is it a driver's car? is it a Corolla competitor? Is it a gateway drug for Audi or a perpetual bottom feeder for 20-somethings?), and I'm not at all sure the merger of FCA and VW sounds good.
Caveat: I loathe Chrysler with the incandescent fury of a thousand exploding suns. All because of the 1976 Dodge Aspen I was forced to drive starting in 1978 when my father died and I, at 16, was the only driver in the house, as my mother never did drive (and still doesn't, God bless her). Since then I've had an admittedly irrational hatred of Dodge, Chrysler, and before that, Plymouth. I also hate SUVs, pickups, and minivans (personal taste only, no criticism implied for those who need/like them, like my wife who drives an Escape), and find Chrysler's muscle cars, which admittedly are pretty solid for what they are, totally out of my interest zone these days (snow belt, mid-fifties, dislike of heavy Detroit rocket sleds that when I was 20 I would have loved).
tl;dr I'd run screaming from an FCA/VW merger, and in all probability it would mean my next car was a Mercedes for sure.