After episode 2, I think I like this series. It's very simplistic and obviously aimed at a younger audience, but then I've never been good at puzzles anyway.
I like the characters so far (though I wish Fukuyama Jun would tone it down...), and like how the show is not really taking itself particularly seriously. It reminds me of Spiral, for obvious reasons, though I kind of hope it won't get as dark as Spiral.
Btw, apparently Phi-Brain is tied with another NHK show called
"Puzzle no oujisama/Puzzle Prince" - wherein pretty boys compete with each other by solving puzzles presented by the anime's main characters. ...okay...