Looks good.
Personally I would try to get some more material on those parallel walls to tone down the reflections. You could use strips of fabric, carpet, etc. It doesn't have to be total coverage, but even a few strips at the most common reflection areas would help alot.
L & R of the seat, directly behind the seat, 1/2 way between you and the speakers (front, ceiling and rear) and corners. Floor to ceiling strips of black fabric would be my choice.
Also some nice lighting, like a few mini halogen spots, especially on the entrance area and the sides. IKEA has some nice cheap ones that you can hide the wires behind the strips of material. Then you can hot wire them to a switch or even control them from a universal remote.