City driving is smooth, like most everyone else it seems. Gear changes are accompanied by acceleration let up, no harsh shifts at all -- except those early morning ones when the CC is warming up. I'd imagine this is good for the tranny as I've had no problems whatsoever in 222k miles so far.
Highway travel driving is a different story.
These cars are meant to eat up freeway pavement at high speeds, and that's exactly how I drive on the open freeway. On a recent trip to Nashville, I was cruising at around 110-115 MPH for about a nice 20 minute stretch through Mississippi. It's amazing that an 11 year old car can hum along at that speed so effortlessly. Amazing cars, these Benz's are.