These pants are more durable than your average pair. They resisted the nicks and scratches that other models got hung up on. They are highly water resistant and dry relatively quickly as well. Though we found them to be tighter than we would want, this could be the right pair for the technically-inclined hiker.
Performance Comparison

This model is good for staying warm on windy days.
Photo: Ben Applebaum-Bauch
Comfort & Mobility
Despite the otherwise solid performance, comfort and user mobility are not necessarily where these pants excel. They do hug the waist, staying put even in high-motion activities and for most regular hiking they are comfortable. However, we found that this slim fit pair feels tight compared to most of the competition.

These slim fit pants look nice but aren't the easiest to move in.
Photo: Ben Applebaum-Bauch
The crotch is gusseted, but we had to double-check the stitching to make sure that is the case. These pants are meant to be slim fit, and they are. Even our skinnier testers found them to be snug and high-stepping activities (e.g., climbing, scrambling) are somewhat restricted with these pants and the thicker material chafes slightly. The fly is not functional. It's too short and too high to use for common purposes. Unzipping it will help you get out of the pants, but we found that it can't comfortably be used when nature calls.

In our experience, the short fly of the Lefroy isn't all that practical.
Photo: Ben Applebaum-Bauch
This pair features an 86%/14% nylon/elastane blend, which is more stretch than average. Though the pants are stretchy, we also found that its tighter-than-normal weave means that they offer a bit more resistance to that stretch than a thinner model.
Venting & Breathability
Despite the heftier fabric, these pants still offer moderate breathability, though we think this pair is better in cooler temps with overcast skies. Other than some mesh in the pockets, there aren't specific ventilation points of which to speak.
When we worked up a sweat, we found that it took longer to cool off and dry off. Though there is no specific securing mechanism, because of the slim fit of the legs, it is possible to roll them up for ventilation without them falling.
Versatility and Style
The Lefroy has decent versatility. They are adequate hiking pants, and their increased weather resistance makes them a good choice in most seasons. They are durable enough for heavier duty outdoor work and stylish enough that we would even prefer to wear them out with friends.

We like the simplicity of the integrated belt and buckle.
Photo: Ben Applebaum-Bauch
Weather Resistance
These pants score highly for their water resistance. Precipitation beads up quickly and rolls off. Because water largely stays on the surface, they are fast drying as well. They even outperform some award winners. For water and wind resistance, these pants are on point.

These pants have solid water resistance. In fact, maybe it's too good; what we found is that they funnel water right down to your footwear.
Photo: Ben Applebaum-Bauch
Features
These pants have a limited but thoughtful set of features. We were a little annoyed at first that there are no rear pockets, but once we got to using the pants, we realized it is pretty easy to live without them. The right thigh zippered pocket is a go-to snack holder. The mostly horizontal zipper is gently angled to facilitate opening with one hand. The integrated belt wraps around the waist and is largely covered by a sleeve except for a few inches in the front. We like the ease of use and the elegant styling of the hook fastener.

The side pocket can be tricky to reach into but is large enough for a snack or two.
Photo: Ben Applebaum-Bauch
As discussed above, we are not sure about why the fly is the way it is. We wish it were more functional.
Value
These pants offer reasonable value. They are a fairly high-performance pant that will offer a lot of longevity for the right user. We think that they are a moderate value.
Conclusion
The
Arc'Teryx Lefroy pants are sleek and simple. Their slim fit cut increases their tech style but ultimately limits their versatility. They offer good weather resistance as well. They are pricey but potentially worth it for the hiker who wants to combine style with performance.