I made some progress on this last week, while on the road to Jasper and to Mount Robson. I've finished all the shoulder shaping (lovely short rows!). It's a seamless top-down sweater: you cast on stitches and knit the back to the bottom of the armholes, then pick up stitches for each of the fronts and knit each of those down to the bottom of the armholes, and then you join everything together on the longest and strongest circular that you have, shape the armpits, and continue to knit the body down to the bottom hem.
That's where I'm at now; in the endless moss stitch of the body. The sweater is getting pretty heavy, though having it on a circular helps -- I can't imagine doing a sweater like this on straights! Wool isn't even a particularly heavy fibre, but altogether I've put, I think, 2.5 balls into it so it feels pretty heavy. And, though it may not look so in the pictures, the semi-solidness of the yarn is becoming more apparent the more I knit, which is nice.
In the picture above, I tried an easy way to keep track of the decreases at the armpit; I took out one locking marker per pair of decreases, and then attached that marker to the decrease as I did it. That way, I couldn't forget how many I'd done and how many I had left to do, and it would be really obvious if I forgot a decrease. I've seen this tip other places but haven't tried it until now, though I think I will continue to use it. This would be super handy for any shaping, like for a sleeve, or armhole, or waist shaping, or even on a hat. I recently bought these Clover locking stitch markers http://www.clover-usa.com/en/knitting-and-crochet/140-locking-stitch-marker.html and I love them; they're sharp-tipped and smooth, and, as with all Clover tools, really nice to use. You don't even need anything fancy to do this, though. Safety pins would work, though I'd be careful with the coiled kind. Even a paperclip would work, if you're careful.