I owned a 98 diesel for 45k miles.
Things I liked, excellent power fun to drive. Very reliable, with the exception of cup holders absolute junk. The car always started even on the coldest days. The transmission requires getting used to, to me it never really felt quite right, driver adaptive, it tried to second quess and learn your driving style, frankly that is not an area that in my mind requires automation. ESP system on the other hand is remarkable, almost impossible to get the car sideways even in the snow and ice.
BUILD QUALITY, not that impressive, quality of materials not very good compared to the pre 96 cars, I hated the seats very very uncomfortable. Bose stereo just average, Economy descent 27 around town 33+ on the highway. Excellent highway cruiser, Drove from Moab UT. to Grand Junction middle of the summer on 1-70 100+ degrees at 125+ mph for two hours temp guage never moved the car was rock solid.
The car overall was good not great. They now are getting very reasonable high teens low twenty's, at that price point I think they represent good value.
Ron
1985 300TDT
1993 300D
1999 E320 AWD WAGON
2003 E55 AMG
2004/5 E320 CDI on order now delivery in April UFB