I own one. A 2003 2.5L manual trans. I inherited the car from my late father, and I was prepared to hate it. (I'm a hard core sports car guy)
I've come to like it very much. It's a drivers car. It's got great throttle response, steers well, shifts well, excellent brakes, good ride and very good cornering (with good tires) . I even find it comfortable. Don't get me wrong, it's not fast, just responsive. Much more so than any of the rental cars I generally get. I prefer this 10 year old Jag to any rental, when it comes to driving dynamics and comfort.
I've had some issues. The 4wd transfer case had issues, easy for me to fix but not for someone else. Jag quoted me $4,000 to replace the TC. I fixed it for $100 by replacing the 2 bearings, sourced locally. Did not even have to remove it from the car.
The throttle body is throttle by wire and quite intolerant of dirt. It goes into "limp" mode and leaves you stranded. A good cleaning helps a lot. If it's too far gone, replacement is the only option. AND, they ain't cheap.
My rear bank cat is failing, along with the rear downstream O2 sensor. The cat is very expensive too. Guys on the forum have had success soaking the catalytic converter in a warm citric acid solution. But, it's a lot of work to remove it. So, I'm putting that off. The cat failed due to a misfire (bad coil)
The headlight internals are made out of a plastic that degrades rapidly. They then stop being headlights, and become owl-patrol lights, shining way up. It took me a weekend, but I repaired mine by removing the bumper, removing the wheel liners, removing the headlights, disassembly, and machining up new adjusters. I then installed HID's. Much better.
130,000 miles, most of which I put on the car. The 2.5L rev's out wonderfully. I use M1, 5W-40 Turbo Diesel Truck in this little engine, as it gives the absolute best UOA's here. Runs better too, as the engine has cam phasers, which are quite sensitive to oil's that are too thin.
Don't spend too much on one. They are really cheap here in S. Florida. $4K gets you a really nice one. And, the later the model year, the better.
No electrical problems at all, as it's Ford stuff.
By the way, the engine is a Ford Duratec, but it has many tweaks that are "Jag only". It's much more pleasant than the Ford variety, more revvy too.