This post and the child one both have very flat-looking faces. Their heads look paper-thin compared to their bodies. Maybe it's that there's almost no shading.
It probably has to do more with Engo's art style for his faces than anything "Wrong" with them. He draws rocking bodies though. His faces are just different from the norm. Its a relief for me though as i'm tired of seeing K-ON imitations.
The uploader already had it appealed and had the appeal was ignored. See [http://danbooru.donmai.us/forum/show/45750 here]. You'll have to put them all together directly from the sources, which we can't delete.