With Arc'Teryx, you are paying for an obsessive attention to detail. Remember - these clothes come from designers who are mountaineers/climbers first (http://www.mountainguide.com/ice/Ice%20Climbing.htm
- picture of Tom Fayle,the guy that Arc'Teryx brought in when they expanded from harnesses to clothing), and marketers a distant second.
They choose their fabrics VERY carefully, and spend a lot of time testing their construction. They also appear to put more thought into design features than their competition. For example, their Theta SK ski pant/bib has something like 13cm of articulation built into the knee! They are easily the most comfortable hardshell pants for moving around in that I've ever tried.
Whether or not they are 'worth' it depends on how much you need, or will appreciate, the subtle features.
Also - the cut of their clothes depends on the line. The alpine stuff IS cut very trim. Their downhill gear (Sidewinder, Javelin, Minuteman, is cut looser, for layering).
And remember, if you come through Vancouver to ski the wet coast, you can always stop in at their outlet (all their clothes are made here in Burnaby) and get your schwag for 35-55% off!