The coupe's are terrific looking and there are very few around due to the high price when new (£45,000!). However, the back seats are a little tight and there is a slight wind noise from the pillarless windows. These are problems you can overlook if you like the coupe shape.
Harder to live with, though, is the reliability of these later models. Between 1993 & 95 Mercedes used wire with insulation that disintegrates when heated. This means you have to replace the whole wiring loom under the bonnet. Ouch!
The auto box has a slight slip between 2nd and 3rd which I'll have to keep an eye on.
The 320 (and 280) engines have variable camshafts which means you get a surge of power after 4,000 rpm. I prefer the more progressive power delivery of the older engines.
The seats feel less comfortable than earlier cars and are covered with leather rather than MB-Tex. The leather is more luxurious, but doesn't last as well.
Parts are also a problem post 1993 as many parts differ slightly from earlier models and are only available though MB dealers. Earlier W124 parts are cheap and easy to get.
On the plus side the E320 Coupe is a rare and gorgeous car. Less wide-boy-drug-dealer than a BMW M3. Altogether more sophisticated. I love the electric seats and the seat belts that come to you when you close the doors.
My advice to anyone looking to buy a W124 Coupe though is buy a 300E-24 non-cat between 1990 & 1993. The engine is more powerful and you'll avoid the wiring loom problems. They're also a LOT cheaper. NEVER buy a Merc without a full service history.