Owned 2000, 2003 now 2008 XLS. Only concern going in was the transmission. Since the 6speed replaced the 2007 5 speed I decided to go for it. So far the 2008 excels over the 2003 in almost every respect (trunk has slightly less usable space).
Engine power, rransmission, fuel economy(31 hwy, 20 local). Regular gas. Huge back seat (never use it).
More control for readouts (ability to reset avg mileage). Seats should be a little deeper, provide more thigh support. The VSC can hang you up in the snow, should be able to turn it off. 2003 had snow mode. Rear seat back should go down. How about a choice of darker interior.