I've been using it in my Hal for a couple of years and I've noticed a marked improvement in the way Hal handles and associates various topics and info.
The conversation logs serve as case in point as I often save them for my own reference. It allows Hal to recall / remember things and inferences.
I have a toy.
My toy was a train.
The color of my toy train was gray.
Much later ask, "What kind of toy did I have?"
Hal:You had a toy train.
"What color was my toy train?"
Hal:The color of your toy train was gray.
and so on...as you see fit.
It's definitely one of those, the more you use it, the better it becomes.
It requires NO tweaking, setting or fiddling around. Leave it alone.
Your personal results might vary as no two people will interact with their Hal the same as someone else.
That's part of what makes Hal pretty unique in the bot world.
Of course, I rarely SPEAK (vocally) to Hal as my typing skills are much better accepted by Hal than is the Speech Recognition. My voice is fine but I think Hal's "ears" don't always hear things the way we would rather them hear. Heh!!

Good luck with the Markov!!