Spent hours doing a classroom scene, without even getting the room to where I was satisfied with it, let alone the pony and the pose and interaction within the room.
The tips I received earlier with describing the room in greater detail (floor, ceiling, walls, wall decor, windows..) has proven to be an invaluable advice, but it’s often not enough, at least not the way I’ve done it.
Then after some (ok, many..) hours of fiddling with that, I decided to do another idea I had, which would focus mainly on a basic flank pose and the tail. For a change of scenery, I plopped down a single line describing a bedroom just to have something other than a classroom going on in the image, and it created lots of beautiful bedroom images. (Getting the tail to how I want it seems to be more difficult in this instance compared to the rather basic pose I tried in the classroom scene though.)
Long story short, prompting difficulty can vary greatly just by what location you try to prompt for. Bedrooms, at first glance for me at least, seem to be on the easier side. My main issues with them though, is that the bed is often malformed, and the size isn’t correct ratio to the character.