I used to wear one as my main coat for years.
>>2384662 is mostly right. They're decent but don't breath great. Tend to be too hot when it's warm but don't add much warmth when cold so you'll need layers. I like the one I have now still but pretty much only use it as a raincoat when weather is heavy.
Beside is a leather one which has similar disadvantages in that it doesn't hold much heat but gets hot fast when warm. It is a much better wind break though. These days I usually only wear it when it's cold and I need to look more traditionally fashionable.
What blows them both away and what I wear almost exclusively in cold weather is on the left, a simple alpaca wool poncho. It's light as a feather. When it's breezy you can pull it tight like a blanket, when not it's warm but breathes excellently. And in anything other than heavy rain it dries in no time. In really cold weather I wear either a heavier weight one or in blizzards wear both. But what I got as a lark many years ago ended up being better than any other coats.
