This is my first Mercedes and what a delight so far. I bought the E500 with the AMG Sport package (larger tires, special alloy wheels, E55 body panels, dual exhausts extensions, etc). The sport package really sets off the looks by giving it a bit more aggressive look while improving the handling of the car. It is very smooth and powerful for a car with just over 300 HP. This is the first new car that I have owned that has not needed any oil added so far (over 8K miles) based on the electronic oil measuring system.
Styling and performance are what got me to go with the E500 vs. the S500 or one of the 500 series BMWs. The combination of size, weight, power, luxury items make it a pleasure to drive.
Put in a backseat passthrough from the trunk as standard and make sure that folddown rearseats are either well publicized or standard equipment. The trunk does not allow for golf clubs to be laid in horizontally (not good for a car this pricey).