I wonder how tall is the princess in the pic?

Based on comments, I’m going to guess that the anatomy issue people are referring to is the fact that there is a joint which is not distinctly drawn.  
(Specifically, if the bend in the leg near the hoof is interpreted as being anatomically analogous to a human’s ankle, then the ball of the foot is missing; the fact that the leg ends in a hoof suggests that Celestia is unguligrade, in which case it would be analogous to the ball of the foot, so the ankle is missing)
 
But I’ve seen a lot of people complain about leg anatomy in pictures where that isn’t the case, so… yeah.

@Background Pony #DB76  
Ragginfraggin no edit button!  
I forgot to say this also might be one of them partially anthro pics, with hooves for hands, so that might explain the leg thing.

@arthurpensive  
I know the lower/back legs are part of it, as they bend… differently to what’s in the pic. If there’s more beyond that, I’ve no clue.

Someone explain to a layman what the anatomic problem is?

I was confused with the thumbnail

Pretty friggen awesome, though

artist, do you even anatomy?

what is this I don’t even