My wife and I have an '06 with the V6 and 6-speed automatic. We purchased it with roughly 35,000 miles on it. We did have an issue with the transmission at 48,000 miles where under hard acceleration the car would slam in and out of gear. It turns out there was a service bulletin on this problem and our dealer replaced the transmission under warranty. I spoke with the tech doing the work and he said that he usually does 8-10 of them with the same problem every year and the problem was in the valve bodies. We were lucky as the factory warranty was 5 years/50,000 miles. The dealership tech said that otherwise we'd be looking at almost $4,500 in repairs. We now have roughly 72,000 miles on the car and aside from the transmission issue, it has been flawless.
I can't say if the 2003 model had this issue, but I thought it was worth mentioning. If I recall, 2003 was also the first year for that generation of "6".