If you were actually looking for a Seville to purchase, I would say no, there are many better choices for a new driver. Having said that, my soon to be 16 year old son will be driving a 2009 DTS when he is able to drive. It is a 1 owner relative's car with 40K miles on it that I purchased for less than 1/2 of NADA value. I like the fact that it is a full size vehicle with airbags everywhere. It was trouble free for my granddad and has been fine for the few months we've had it. Besides driving it from AR to TX, it's only been driven for 1 tank of gas. We detailed it inside and out, put new tires on it, and it has been sitting in the garage since. It is powerful, but not blindingly fast, and definitely not quick. 22-23mpg on the highway, 16mpg around town. By current efficiency standards it's a pig.
If the Caddy had not been available for $7900, my budget would have been between $5-9K to spend on a third car to share with a new driver. I would have been looking at a used 4 cyl Altima, Accord, Fusion, Mazda, Volvo, or Subaru.
Side note anecdote. I have a different relative who has owned a 2004 Deville since new, it currently has over 140K miles on it, and it has been trouble free except for normal maintenance. Similar engine architecture as mine and the one you are looking at most likely.