My (girlfriend's) favorite jacket (to steal)The Ghost Whisperer is like the iPhone of ultralight backpacking. Sure, it's overpriced. And sure, it's not the most durable option out there. (If you fall in a patch of briars while wearing it you'll come out a downy bloody mess. Source: me). But it's light and sleek, it has all the features you need, and it gets the job done.
In terms of sizing, I'm 5'11" and between 150-165 (post- and pre-thru-hike, respectively) and the medium was roomy. I can comfortably layer a fleece underneath. However, I would have preferred the torso to fit a bit slimmer, as it could be drafty at times. The sleeves and wrists felt a bit narrow at first, but they were plenty spacious towards the end of my hike, once I'd emaciated myself sufficiently.
Now, note that when they say "Water-resistant", they mean "moisture resistant". This is not a rain jacket. Nor would I recommend layering a rain jacket over the Ghost Whisperer while you're hiking - you'll sweat straight through it.