This is one of those shows that you know is mediocore, but nonetheless, you still find yourself enjoying it.
The premise of the show is interesting, life threatening puzzles set up by a mysterious organization; the POG. It's definitely different in its own way. The show uses it's 26 episodes well, so the pacing is pretty good. It takes its time to flesh out the main characters, and once the main villain enters the show, things pick up fairly quickly, and it becomes much more interesting. Since the first half of the show serves as build up, it's fairly episodic, and therefore a bit more dull, since nothing of major importance to the plot is really occurring. But, once again, towards the end of the series the plot does pick up. I epsecially liked the twist the creators did with the whole Orpheous band overtaking Kaito's personality. While not an original idea, it did spice the show up, and really made things more interesting. This show could have scored much higher for me if it weren't for the ending. It did have that potential. However, the episode takes on the whole 'friendship conquers everything and everything works out and i'm so happy' type feel. It's really cliched, and the whole spiel just feels anticlimactic.
The puzzles in the show however, were creative and interesting to watch, so that added to the general appeal to the show.
The style was refreshing, again in its own way. It wasn't all moe (which I personally don't really like), so the character designs were definitely original. However, due to the relatively low budget of the show, the animation wasn't all that consistent, and there were a good number of still shots. Otherwise it's decent.
While the soundtrack itself isn't all that memorable, it did fit in well with the mood of the show, and helped the overall feelings of tension and whatnot when Kaito was solving the puzzles. So the music did its job, but it never went beyond.
This section is a tricky one. At first, when I got introduced to the characters, my opinion of them ranged from bland to downright obnoxious. The characters are all over the top, but then again, that's the whole angle this show has taken. As the anime progressed though, I got used to them, and actually started to like them. There are a couple of episodes that stick in my mind, when Kaito is experiencing visions, that really show how well the characters interact with one another. In those particular episodes Nonoha particularly shines, and takes her place as the main female lead. I liked that the creators didn't make her a puzzle solving genius as well, who would always be overshadowed by Kaito. That would have taken away from her character and would have just made the show more cliche, since she is the female lead. Instead she acts as more of Kaito's moral support, so she grows on you as well.
Rook was also an interesting character, though I feel he was the most inconsistent one as well. Though his character itself wasn't all that great, his arrival really changed the gears of the show. And everyone's reaction to him was equally as fun to watch. However, his personality really did confuse me. His motivations are conflicting; they don't make all that much sense, and his whole personality changes, particularly in the last two episodes. He was mainly good as a plot device, and developing Kaito's character, not much else.
I really did enjoy this show. While it does have its obvious flaws, and maybe unoriginal, it's still an enjoyable watch, particularly around episode 12 onwards. Don't go in expecting too much, that mindset will only lead you to see the disappointing apsects of the show. But if you're looking for some time to waste, look no further than Phi Brain.
The only thing I really don't understand is how the second season will be played out. With the POG defeated and Rook's grudge resolved, I honestly don't know what direction the directors have planned for the second season.