WTG. I love the in-wall rack. Very sweet. I still SOOOOOO wish you would do a center tower. That will be a HUUUUUUGE improvement. The biggest you can make, IMO. HUUUUUUGE. Maybe someday long into the future.
So, with the above in mind, Im not sure what that cabinet is doing in the middle. For storing movies? If so, good, that means its not utterly necessary to be placed there for future purposes.
Also, posters are cool. I have one on the back wall. However, if you put them on the sidewalls, you may get more visual glare in the periphery, more reflection of audio, and take up space where treatments could be mounted.
You might want to acoustically treat the room eventually. HTs are desired to be pretty dead, even more so than music setups, typically speaking. DIY is the cheapest, and otherwise they are not cheap. IOW, I wouldn't recommend spending more on treatments than on a speaker upgrade. But. believe it or not, there is as much $ in my HT treatments as there are in my HT speakers (not including sub). And Im using 7 speakers. I've found that the more I tame the room, the more easily I can crank the volume, because when I hear irritating sounds (which are probably often reflections) I don't want to crank it further. YMMV.
