Don't know him, but I'd agree, there are many ways to screw up a room.
From what I've read the ideal dimensions would be some multiple of 1 x 1.625, with the latter (the "long wall") where the side speakers would be positioned.
Having worked in a few recording studios, the engineers always tell me "no parallel walls".
I moved my audio system down to our family room, creating a "man cave" and pursued multiple upgrades, each one easy to incorporate into the room...until the new sub woofers arrived. The room is roughly 24 x 26 and has all sorts of zones where certain low frequency tones resonate greatly, others where I have big dead spots. I am about 90% to where I'd like to be, thanks to installing bass traps from ATS Acoustics.
Good luck with your project!