Essentially a 745Li with a bigger engine, well after all it is just a refreshening. After trading the 745Li for the 750Li, the major difference is power. Its great handling, but some what indifferent to bonding with the driver. It kinda just does its thing, not much feeling... Anyways, compare to 2005 S500 definately better performance although only 6 speed as oppose to S500's 7 speed its still smooth. S500 has a much more comfortable suspension. It comes with 4 year warranty and the best part free maintenance. The BMW free maintenance covers a lot and will save you a lot too because it covers new brakes, oil changes, minor and major tune ups.
The light style is better and more agressive than the 745Li, its got better performance than S500. Huge back seat. The driver seat has soo many adjustments that it is almost impossible not to be comfortable in it. Comfort seat is an Option in the 750i short wheel base one.
Maybe some extra suspension setting like a LUXURY mode. Germans learn to adapt cuz the seats are still hard. Could use softer leather on sitting surface. Improve that Idrive, the Navigation part is still some what complicated.