I traded an '04 Mercedes e500 for the 545 and am happy with the decision. The 545 is sportier, a bit quicker and grippier on the roads. I have to say, I think the Benz has a few things over my 545 - interior and exterior design primarilly, though the "Banglisms" (designer) on this car are growing on me...
Bluetooth - if you have a bluetooth phone, you have to get connected with this feature. The most under-promoted, awesome feature aside from the car's engine itself! Justifies the iDrive -
Cupholders - sounds petty, but they could not have been designed more poorly by my 14-month old... Horrible and a source of frustration as cans wooble, bottled water doesn't fit and coffee is a non-option.