These short naps just keep feeling weird. The feeling of time gets really warped during them and I feel I'm constantly waking up. I'm not sure if I really am waking up. I also feel that I'm in between sleep and awake for loong streches. It's only about 90 minutes, but it feels like a full night. It's probably only my changed perception as these first 90 minutes are completely forgotten in a normal night of sleep.
But when it comes to mental clarity and restedness, I feel good. I've had some waves of feeling tired, but they were really short, like few minutes and I never really had to fight to stay awake. Nothing near it. It's problem-free so far. I feel like I could permanently changing to biphasical as it makes me a few hours more already. Also big thing for me that got me interested in polyphasic sleeping was the fact that I could stay up all night. I really enjoy night in the viewpoint of solitude, silent morning walks in the twilight, etc. but with normal sleep patterns these were out of my reach, as you need to be awake at day normally. But polyphasic sleeping including the kindergarten version, biphasic sleeping really overcome this problem. There's 16 hours a day awake, more continuity as you're never out for that long, more effective hours where you're feeling rested and energetic.. This is great stuff. It's like having a cake and eating it too.
That said, I will go for Uberman in July, no matter what. Biphasic is nice, but 2 hours a day is what is all about, as well as instant REM. Instant REM is the holy grail I'm after.