I would say that although a head shape and size is somewhat arbitrary (though oddly it is the most favorite and common feature people look at first...go figure.
as in "you don't ride a head" hers is plain but not unpleasant. she has nice, large eyes to go with, and it is not ugly.
What her conformational shortcomings say to me even through the hair, though with the hair, they either may not be as bad or they may be worse is that she has a weak and short hip angle. She needs more depth of hip and then her longish back will not look out of place so much. Also, though her tailset looks low, it would also look more appropriate if her angle were more "right" and in proportion to her overall build, as it would naturally come up.
Her coupling and loin area look "off" as a result of how she's made in that area, and I don't know the whys and the hows or how this will affect her soundness, it just looks wrong to me. I believe it affects her ability to get under herself, but then again, oftentimes horses that are made poorly perform just fine, even at the things they shouldnt' be able to do if you go by the book.
Her front legs appear to be over at the knee.
Her neck ties in low and has a dip in front of the wither. It appears to be ewe-necked as well.
I know this sounds like a lot "wrong" but I would say she is overall not that bad. Depending on what her sire and dam look like, she could be well hiding some nice genetics, but this is not a mare I would choose for breeding based on her appearance alone. I know you did not ask for that decision, this is just "my opinion."
There's just too much off about her. If you want to clean her up a little bit and clip her, you may get a bit different opinion or better idea of what her build is. All in all, before you go making decisions, it's best to learn yourself what to look for as well as ask opinions of people who are better qualified and can see her in person.
The hair could accentuate some flaws and hide others, but these things are what I see on this horse.
Liz