I owned a 72 Sedan Deville for awhile as a daily driver. I can tell you that I never ever had any issues with that car. The drivetrain was solid and dependable, but for some reason the damn Rochester carbs they had on those cars were a pain to keep adjusted. I can't count how many times my rebuilt unit kept backfiring, or dieseling when I would shut the car off. I had the same exact problem with my 68 Cadillac Deville carb, which are similar in design, the 68 also would diesel upon shut off, and I could never seem to stop it from happening, even after taking it to a mechanic.
Besides for the cars excellent power and performance, I hated the interior! It is so bland and boring, the seats were nice and the interior room in the Caddy was massive!! But the quality of everything seemed a bit low compared to the 68 Deville I owned at the same time. The 72 has hardly any chrome, or anything exciting to look at on the inside. All of my door panels had small little cracks in them. I did like the stitched headliner though. What I did love about the car was it's heaviness, the doors, hood, and trunk felt like a tank. The doors are really heavy to open, the same with the huge hood, which takes some serious muscle to lift open.
The ride quality was decent, but considering it being so big, the car didn't ride as serene as I hoped for. Going over bad streets tented to rattle the interior, it wasn't pillowy at all, a nice highway ride, but I am sure a Lincoln Town Car of the day would have been a much better ride, or even an older Cadillac, because I remember the year I sold off the 72, I was checking out a 70 Sedan Deville, took it for a test drive, and that car had an extremely nice ride, going over huge pot holes and road imperfections didn't once jolt the Caddy, it rode right over them as if they were never there. My 72 would of shook, and felt like it was being hurt by the bumps and pot holes, rather than fighting them off one by one like the 70 did.
I knew an old co worker than had a 75 Deville he drove to work all the time, we would hop in his Caddy and get lunch during our breaks. The interior in his car, looked and felt much better than my 72, the styling was more impressive because it had some, unlike the 71-73's!. It even rode a little better than the 72.
Personally I would look at the 74-76's for a better ride and interior looks/comfort. Exterior styling is all subjective.
I wouldn't mind owning a 76 Coupe Deville though, I saw one at a car show the other day, and man was it beautiful. Also the 71-73 Eldorado's are bad ass, and are much better looking cars than the Devilles of the 70's IMO.