I agree 100% with Mr.4pt. Just to clarify, the ghillie suits I' m talking about are the ones made from strips of burlap and material that is sewn together and looks like something a military sniper would wear. Some people call the " leafy wear" type suits ghillies suits.

My wife bought be one of the ghillie suits out of Cabelas a couple years ago and as great of an idea as it was, I had to send it back, because there was no way I could bowhunt in it.
1) It was heavy! By the time I got it all on, I felt like I had someone riding on my shoulders.lol The head piece seemed especially heavy.
2) The strips of material on the chest and sleeves made it almost impossible for me to even draw back my bow, much less shoot it without the string hanging on the loose material.
3) It was hot.
4) The thing itched and smelled funny!

Jersey to answer you question, yes I think it would be great for gun hunting in cold weather. If you were doing alot of still hunting with a gun or just gun hunting without any type of stand and just want to be able to sit by a tree, then the ghillies suit would be perfect, in my opinion, as long as you wore it mainly in cold or cool weather. I' ll have to admit that the thing looks cool once you get it on. My buddy said it looked like some kind of a swamp monster.lol