The XD is almost bulletproof and reliable as anything. The old 250 crossy is as tough as nails, and the Bosch Stromberg carby with manual choke and the dual-advance pointsless Bosch distributor make the car pleasantly easy to tune and keep running sweet.
The performance is a bit doughy compared to the XE and XF, which had the twin-throat Weber ADM carb, especially running on LPG, however it still has enough get up and go to hold its own in town, and be a pleasant cruiser on the highway once it gets to speed, and can still pull a pretty good load, albeit a little sluggishly. It is definitely an underpowered old tank that had not had the potential of its massive motor fully explored yet.
The old XD wagon handles alright for a leaf-sprung station wagon, however the 5 turns lock to lock of the manual steering box is tiring in cities like Canberra where I drive it, and doesn't allow for precise, agile driving. The same car with power-assisted steering (which has only 2 and a half turns to both locks) is an absolute weapon that actually HANDLES rather than just steers.
It is a fairly economical vehicle all aspects considered, giving reasonable mileage on petrol for a car its size and engine capacity, and amazing economy on LPG... using only a little over a full 50 litre tank of gas for a 450km round trip, costing about $50 in total.
The body/chassis and suspension are rock solid, having survived many a bingle with little more than a couple of cracked bumpers.
One annoying letdown that unfortunately plagued all X series Falcons up to the XH ute of the 90's was the perpetually breaking door handles... they either snap at the plunger, tear at the hinges, or have the retainer for the return spring break off... in all cases rendering the handle useless from the inside. Also, the door hinges sag over time, making doors a pain to open if the hinges aren't adjusted every so often.
The interior is adequately comfy, however the seats can be a little strenuous on some cars on the long haul (depending on wear, seat covers, style etc), and the 6 seat column shift model I own does seem to overwhelm you a little with the sheer amounts of space around you. And also the seat adjustment is unfriendly to those who are short of stature.
The interior in the XD is rather poorly organised and less that ergonomic compared to the XF model, with an old style round push-pull knob for the headlights under the instrument cluster, and the same knob for the hazard lights... WHICH IS LOCATED MILES FROM THE DRIVERS SEAT!!! Also I find the indicator stalk to be out of comfortable fingers reach on the XD when it is flicked forward to the hi-beam position.
All in all, despite the flaws that are to be expected from what was a revolutionary new design in its time, the XD is a solid, rugged, reliable and pleasant vehicle that is almost unstoppable, and if looked after, will survive long after all of today's flimsy 4-wheeled sardine tins have been turned into mobile phones and tinfoil...