Burda 08/2007-112 coat muslin

I'll admit, I'm not the best at making muslins. I know, I'd probably have better final outcomes if I did, but it is easily my least favorite part of sewing. Still, when one making a coat, even I think a muslin (test garment) is in order.

Here is the line drawing for Burda 08/2007-112.  As you can see, it is a fairly straight cut coat, shaped pretty much just with the belt, although there is a small dart that is hidden under the lapel that provides a small amount of shaping in the chest.

Here is an old sheet, cobbled loosely into the form of the coat, and tied with a random sash. Looks a bit like a bathrobe at the moment. My fit concerns here are all in the shoulder and sleeve. The shoulder seems to be slightly dropped, and I'm not sure if that is style or size. I do have narrow shoulders in front. The fold falling from the shoulder line is suggesting too much fabric there, so I need to consider that. The sleeves also seem to be twisting. I have no idea what that is about.

From the side, the sleeve looks great, and the hemline and side seams fall straight and even.I'm wondering if the collar is falling too far back, though.

In back, it looks OK, although there are a few wrinkles in the armpit in this pic. I'm not sure if those are real or just posture related.

With my arms forward, it looks OK, but feels a little snug across my back and rear. I think I will release the center back seam from about mid back all the way down and add some width there for movement ease.

What do you think?