Hi David,
I've only had the XF-S diesel Portfolio but I have to say it's delightful, easily as fast as my previous 4.2 V8 S-type, fantastic handling for a big car , quiet, comfortable with a lovely interior.
Downside, probably not as economical as you'd expect for a diesel, I average about 37 mpg on a 40 mile round trip to work and a fairly easy drive.
Hope that helps,
Mike