Okay, I would suggest waiting for the newer model. If you look up the international website, they have a full upgrade ready - Sensus, ACC and the whole lot, including a slightly more powerful D5 diesel engine (215bhp/440Nm).
Maintenance honestly isn't much at all. Availability of certain major parts however is a negative, because the lead time can easily run to over 30 days. If you have a backup car and don't mind waiting a little, not a problem. Again, this is only an issue is you need say, a door, or windscreen replacement. Regular spares are readily available, and maintenance, as such is next to zero, including the cost. The free service package truly covers everything, and I have not yet seen a case where there has been a charge to a user, apart from any accessories order of course.
After driving the rest of the cars in it's class, I can say the it certainly is the most comfortable, though the new F10 5 series bullies it's way into my sentences each time as it truly is a remarkable car - room and comfort-wise. I've sampled the 525d, the XF V8 and the E350 CDI. The XF D I haven't had a go at, so I can't say much, but purely on numbers, it eats the rest alive. Feature-wise though, the XF has almost all of these beat! And there's a new 2.2L XF I4D on the way too.. The E350 CDI was absolute rubbish - comfort, handling, space, feel, everything. Nothing about the car appealed to me. The new Audi A6 debuted too recently for me to have a go at it, but it definitely looks promising!