-Has Many, Many Buttons, some of which may be extraneous
-Not long enough to get hung up in a wheel, chainring, or other moving bike component
-Armholes get very tight when layered over wool baselayer, longsleeve t-shirt, shortsleeve t-shirt, and hoodie
-Insanely, ridiculously warm when you're actually riding a bike
My Old Navy peacoat is an awesome peacoat, and really good at keeping me warm. It was a really great gift, and I'm still enjoying it more than a year later.
However, given an intended ride distance of more than a couple of miles, unless you don't want to go very fast or it's ridiculously, insanely cold out (colder than -13 C, for example), it's not an optimal cycling jacket.