Room shape and acoustics.

[Automission]

So, my HT room has sloped ceilings. At the moment, my Tv/Speakers are inside an alcove where the ceiling slopes down. Now, I was wondering how will this affect acoustics and sound quality once I upgrade my speakers?
I was considering leaving it how it is, with the Sub and front/centre speakers all inside the front of this alcove. This is the basic shape, both on this side and the side opposite where I sit.

The Layout

(please excuse the mess, this isn't a dedicated Ht room)

Now the other sides are flat walled, however one is somewhat boxed in, leaving no space. The only other flat surfaced wall is where my window is. So, should I bother moving the position of my setup, or will these ceilings cause no obvious problems to my sound reproduction?

If you want more pictures of the room layout, please just say.