I used this pant on a 4-day wet spring camping/hiking trip in the Whites of New Hampshire. They are tough and highly water resistant yet extremely comfortable to hike and climb in. The workmanship is superb and the fit seems true to the indicated size. I thought that with the high water resistant rating I would feel sweaty but this was never the case, even in warm temperatures. I used them in the rain and sat directly on wet mossy rocks but there was never any water penetration. With this Arc'teryx pant you can forgo carrying an extra rain pant (unless you intend to hike in a hurricane) which saves weight and space in your pack. The material used throughout is slightly stretchy. I generally avoid stretchy hiking pants - not liking what happens to the leg parts when you load up the pockets - but the Gamma SL exhibited only a very small degree of this droopy drawback. The bottom of each pant leg comes equipped with a drawstring and a neat little lace hook thus serving as a built-in gaiter - another space/weight saving feature. There's also a built-in nylon belt that goes through a waist tube rather than traditional belt loops and two main zipper pockets, two small zip side pockets, and a right zip back pocket.
Although the Gamma SL Hybrid pant is the best such garment I've ever owned, there is still some room for improvement. I'll start with the lack of traditional belt loops. I like to hook a pocket knife to such loops and there is no way to do this with the belt tube. They should have at least included a knife/key ring somewhere on the waist. The small lower side zip pockets are located on the legs and allowed a pocket knife to move around annoyingly while hiking rendering them useless for such a task. I suppose a pen, comb, or even a small compass would be okay in these pockets, but nothing with any weight to it. The main zippered pockets could be a little deeper, but that's just my preference.
Even with the few minor drawback described above, the Arc'teryx has become my favorite. Are they worth the $200 price? I would have to say maybe but will probably purchase another pair anyway - preferably when they go on sale.