Kind of excessive production value. I've been posting lots of stuff with odd time signatures, most of which are very calculated planning on my part; here, the odd times for the B and D sections were just because those were how the guitar riffs I made up "on the spot" (not actually improvised while recording, but basically improvised and then immediately recorded afterwards) turned out.
I continue to be amazed at how good the mono mixes turn out. In fact, this one sounds a little better than the stereo original, because the main guitar has some excessive stereo reverb. The keyboard at 0:20 sounds much nicer in stereo though, as does the wash at 0:42.