I have been driving my ZX 1.8i wagon for the past 8 years, albeit not often enough. The car takes a long time to run-in.. at least 20,000km.
No major or recurring problems. Only remarkable thing that happened to it was that I smashed the oil sump by when it hit a tilted manhole cover in Seremban (going into the curve opposite the train station). Brand new oil sump cost me RM1200.
Parts are cheap if you don't mind using Peugeot parts. It is interchangeable. Any differences would be very minor. Recently bought link rods and tie rod set for the front (left and right) at Asli Auto for about RM500. Notwithstanding, it is still a little bit more expensive than parts for my e21, but easier to get. e21 parts are getting more difficult to get.
Maintenance wise, go to the experts. Just as with your Bimmers, you need people conversant with the idiosyncracies of the car. My mechanic for the Citroen was one of those trained in the earlier years when ZX was first introduced. Many a time he has saved me a bundle.
The bad press Citroen receives can be attributed to the way Directionless handles the franchise. I only went to them once. I figured that they would be just like AB was in the 1980s.
Handling wise, I think its better than Bimmers - the car was designed for twisty roads, cobbled streets etc as what you will find in France. Heck! Its the precursor of the Citroen Xsara, the WRC this year and last year which is only just now being replaced by the C4. ZX too was also successful in the international rallies in its day.
After all that, I do have one complaint - my ZX is way underpowered...