Customers often send me drawings of their rooms. One of their biggest worries seems to be when the room is not symmetrical. And their greatest angst seems to occur if one side of the room opens wide into another part of the home.
Because one side of the room opens into another, the question becomes how in the heck to get good imaging if one channel has a sidewall while the other does not?
I am here to tell you you're probably luckier than most.
Through setup we can always work around the sidewall problem using absorbers or diffusers or simply positioning. What we cannot easily fix is the bass problem. Enclosed rooms generally have lousy low frequency support. Between the standing waves that bunch up at the boundaries and the lack of room for long wavelengths to do their thing, bass suffers.
Those lucky enough to have a room where one wall opens into the rest of the house generally have plenty of area for bass to prosper.
Solving the sidewall asymmetry is easy compared to the bass problem.
If I have a choice, I'll go for the open room every time.