The XM lacks the style of previous big Citroens, its styling is not 'ageless' in the way of the Traction Avant, DS, SM or CX. However, it still possesses a degree of quirkiness. I particularly like the 'band of light' and general stance of the car. However, the flat slab of a bonnet is rather bland and I wish it had continued the tradition of fared-in rear wheels.
The cabin is supremely comfortable and simply huge, with very high equipment levels. Whilst the colour and design is rather gloomy and lacks the flair of the CX, for a conventional interior it does work well ergonomically.
With a 2 litre (albeit turbocharged) engine it's not particularly fast, but it's quick enough and handles well for such a large car. My biggest criticism is the dropping of the diravi (Variable assist, high ratio and power to centre) steering from the CX in an effort to make the XM more accessible. It makes it less manoeuverable and slower handling than it would have otherwise have been. The other aspect of driving which warrants criticism involves the headlights which are very poor when dipped.
It's not the most refined car, but it is quiet enough, whilst the ride is second to none. This latter can be improved still further by changing the centre spheres for ones with higher pressure and by various other tweaks. I have not replaced the 4 spheres on the end of each wheel with 'comfort spheres' as, in my opinion, it makes the car under-damped.
Reliability wise, although it has a disastrous reputation, I have found it to be very reliable and cheap and easy to service. The build quality feels solid (it's a Mark 2 which in respect of the interior and electrics is much better than the Mark 1). For example, the doors are well sealed against the ingress of rain and mud from the country roads I drive on.
Overall, the XM is different, provides decent performance and handling, has proved to be reliable and well built (I understand it also has a very good crash rating-although I hope I never have to test that) and above all is extremely comfortable.