I have had a 190E 2.6 (1987 model) for the past nine years and thought it was great.
My particular beast was never very quick off the line but once on the highway it was fine.
I regularly run it at about 120 - 130 kph (75 - 80 mph) and it just purred over with no fuss. There is some engine noise but it was, in my opinion, more of a reassuring hum that all was well rather than an irritating intrusion.
I drove the car from Vancouver to California with no drama and no concern that I was pushing the car to its limits. When needing to accelerate to overtake, it always had plenty to spare from 120 kph.
I now have a 2000 m.y. W210 E430 so performance in the 190E seems a little deficient but it is still a good car to drive around.