I've tried this for a few months, and cannot recommend it. One of the only things I really enjoyed was how vivid the dreams were. However even after the experiment, I found it difficult to stay awake during important parts of the day, and felt like I could easily slip back into the polyphasic cycle.
Same. In particular, I found that I could induce lucid dreams pretty much on command. At the same time, I noticed (what felt like) a correlation between this ability and generally being wrecked with exhaustion.
In retrospect, I'm not sure if my dreams were actually more vivid (or if the lucid ones occurred with actually greater frequency), or if they just felt that way because I moved so quickly between sleep and wake, so the dreams weren't cleared from my working memory. (If I had to wager, I'd say it's more a matter of recall bias than actual improvement in dream quality.)
Perhaps it takes a long, long time to adjust to a polyphasic sleep regimen. Perhaps some of us just can't do it, due to the idiosyncrasies of our physiologies.
An interesting article by a fellow HN commenter, who did an extensive self-study on sleep quality (including thoughts on the costs vs. benefits of polyphasic sleep):
