2 years ago I bought this car for my wife for her birthday because she has always wanted a Jag. This is just a beautiful vehicle. It does have it's quirks but they are far overridden by the cars elegance and luxury. All her local driving is done in her Maxima and long journeys are taken in the Jag. This is a touring car and is designed to be driven on the highway for long distances at cruising speeds(within the law, of course). Jags have had a horrible history with quality control that I believe Ford ironed out when they took over. Neither of us has ever quite driven a vehicle quality and luxury which is why it is probably the best car we ever owned.
Strengths: Fun to drive and very fast on a dry road, zips around trucks like a breeze. Looks great, attracts, "Nice car, man!" comments several times a week. No mechanical problems, very nice sound system. And it actually does achieve 21 mpg on the highway.
Weakness: does not go in the snow, at all, not even a little bit. Rear wheels just spin even with a light dusting. Not great in the rain, either.
I bought this car in 2007 (5 years old, 45k miles). I paid $18k used, less than my friend paid for her new VW beetle and i'm driving a gorgeous luxury car. The only visible flaws were cracked walnut paneling and I had the overhead cloth replaced. Then I have proceeded to drive the heck out of this car. I've commuted with it 500 miles/week for the last 7 years, hauled my scuba gear in the trunk (in a plastic bin), and many road trips with or without camping gear. One reason I bought the XJ8L is the big back seat; at that time anticipating large passengers. As I started doing Triathlons I discovered just taking off the front wheel I can fit my entire racing bike in the back seat easily, quickly, and with little impact to the vehicle. I've had two consistent problems- with coolant sensor light and fuel cap light- that after several fixes I have just decided to ignore. The only problem I ever had driving is when I took an 1500 mile RT drive to Key west; since the car was built for a tall british man (and I'm an average American girl) after 600 miles my back hurt cause I didn't fit right. It's now 13 years old and near retirement at 220k miles; since the right rear wheel bearing gave out, will likely replace vs. repair.
Overall very pleased and impressed with this vehicle. As a first-time Jag owner, had not considered a Jag in the past, had previously owned MB, Audi. Have to say I was pleasantly surprised with this vehicle. So far, my ownership experience has been great and has exceeded my expectations!