I'm male, 5'10" tall, 150-155 lbs, athletic build. Bought a new 2009 model.
(I didn't buy it at Backcountry.com (I can't because I'm outside the US), but the reviews on this site helped me a lot.)
I haven't used it much because I just got it posted to me, but it seems fantastic for day-to-day wear. There are huge discrepancies on sizing that I want to help clear up, along with some factual information that I hope to address.
When worn, my jacket goes halfway down the fly/zipper of my jeans. The jacket is not too long, nor too short. Buy a medium if you're between 5'8" and 6' tall, and 145-170 lbs. If you're 6' tall, you may want a large, as the jacket would show your stomach if you raised your arms towards the sky.
Sleeves are slightly too long. When my arms are at my sides, the sleeve goes down to my knuckles. It doesn't bother me at all though, so I won't even use the velcro adjustments for regular wear.
The jacket fits well. It's not an athletic cut, so it doesn't fit really close. However, it's not supposed to be an athletic cut. The material is thin enough that you don't look bulky when you wear it, and it doesn't look like there's too much excess space under the jacket. If you wear any type of long sleeve t-shirt, jumper ("sweatshirt", hoodie), or knit (sweater) underneath, it'll fit well.
Inside the jacket, the back and other areas is lined with a thin fleece/microfleece material, while the chest area is covered with a soft synthetic fleece-like mesh/net. If you stick your hands into the 2 hand pockets, you can feel this mesh material. You can also see your hands if you look inside your jacket. This mesh material inside the jacket extends from the bottom of the jacket, right up to the shoulder, so the pockets can actually fit a lot of stuff (as long as it fits through the opening of the pocket). For example, you could fit a long flashlight inside the hand-pocket, a rolled-up document, etc. For the photographers, you could even fit a monopod (collapsed) if you wish! There's also a chest pocket which leads to a mesh material.
I think the purpose of the netted material is to increase circulation when you open them up. From reading reviews here and elsewhere, the jacket is great at blocking wind, but isn't very breathable. This is probably because there's some form of laminate layer covering the outer Apex material. You can get laminates that are more breathable than others (eg: Gore-tex), but generally speaking, laminates aren't as breathable as regular fleeces, or most softshells that don't have a laminate. Anyway, if you feel hot, you can cool down by unzipping all 3 pockets. That will let out the "condensation" built up inside the jacket. However, then you may get cold because the cold can now enter the jacket. That's the catch with this jacket. This jacket may be more wind resistant than Windstopper, but Windstopper exists because even for a laminate material, it's breathable. You can either get this jacket with more wind blockage with less breathability, or less wind blockage with more breathability. You decide.
Some jackets use Windstopper laminated to a better outer material, so it's still more breathable than this jacket. However, they're over $200.
If you know you're going to be really active, I think it's better to buy another jacket with a more athletic trim. These jackets should fit closer to the body if you need the breathability. This jacket fits close, but it's still "standard cut."
In terms of weight, this jacket is like a Polartec 200 fleece based on the feel of the jacket. If it's not windy, it'll keep you as warm as a Polartec 200 fleece. If it IS windy, it'll keep you far warmer.
Hope I was helpful.
