Seeing as how Rab is UK based, they come with a european cut (a bit narrower in the shoulders/chest when compared to american jackets...the zipper is even on the other side with Rab!) , so they are definitely not boxy like patagonia or north face. When I compare my Arcteryx with my Rab, I actually find the Rab one to be even more athletically cut, as the torso is even more trim. The arms are perfect IMO. I have monkey limbs (for reference, im 5'9, but only have an 18.5 torso, yet my sleeve length is 34") With my arms to my side, the sleeves on my size Small Rab still go past my wrist. The cuff is diagonally cut, with the palm side of the material being slightly past my wrist, and the other side having enough material to go about halfway down the back of my hand. Needless to say, when I raise my ape appendages, my wrists are still covered and protected from the elements. To sum it up, if you're a slim/med or otherwise athletic build, you'll love the cut.
What size are you? I'm replacing my Rab drillium (Jacket, not pants) with a Rab Latok Alpine (better hood on the latter), and will probably let the drillium go. I'm a size small. Just send me a PM if you're interested. Thanks