Somewhat surprisingly, franchise accomplishes the improbable by applying a shonen action-style flair to the very cerebral “sport” of puzzle-solving, to the point of making the normally sedate hobby into a relatively thrilling endeavor. As much as it sounds like an Anime News Nina parody, it actually can be entertaining, though one cannot take it as seriously as it takes itself.

When the series works, the puzzles are almost invariably responsible. Every episode has one or more highlight puzzles (typically but not always Philosopher's Puzzles) and often depicts or refers to several lesser ones, which can range from classics like tangrams, mazes, find-the-paths, and “who's lying and who's not” logic challenges to more recent favorites like Sudoku and slide-the-car puzzles to more innovative ones, such as a color-based variation on the old shade-the-box puzzle, one which involves stacking scale buildings under certain restrictions, and one which involves grouping paintings by artists' initials to spell out a coded code. Many of the puzzles are done in English in the original form, and only a few of those using Japanese actually require any working knowledge of Japanese; for instance, one puzzle requires knowing how a Japanese keyboard compares to an English one, but another that involves putting kanji in the right places in a circle can be done based merely on the way the kanji looks, as it involves making a chain of kanji with two elements where each kanji has its elements identical to ading ones in the adjacent kanji. (A rough English equivalent would be to do the puzzle with syllables, such as hydra-drama-macho-choker.) The puzzles are usually ones that viewers can solve, too; I tested one of the Sudoku and one of the other grid-based puzzles this way and found them both to be solvable at a medium level of difficulty.

However, the whole puzzle-solving structure can also be a problem. While characters show off their impressive intellect by recognizing and even quickly solving both common and obscure puzzle types, in certain cases the plot forces them to be stupid just to heighten tension; that someone who is a puzzle master would not instantly recognize a Magic Square scenario strains credibility past the breaking point, as does failing to quickly recognize that consonants like Yu-Gi-Oh! aimed at somewhat older audiences, except with puzzles instead of cards.

The cast does not help much, either. The main cast are a decent enough bunch, if mostly a collection of common shonen archetypes: Kaito is the bad boy-flavored puzzle master with the tragic past, Gammon is his hip rival, Cubik Galois is the boy genius/science geek (although the robot he rides around in is pretty cool), and Ana Gram (yes, that's really his name) is the cross-dressing oddball. Nanoha seems like the typical athletic/martial arts expert-but-can't-cook childhood friend who can manhandle just about anybody, but her photographic memory and occasional keen insight result in her actually being more than just a hanger-on in some of the puzzle-solving scenarios. The other ing characters are even more pure stereotypes, with the only one who is even the slightest bit fresh or interesting being the class president, as are most of the villains. Some of the character dynamics can be interesting (especially how Gammon interacts with both Nonoha and the Giver Erena), but these are still pretty basic and there isn't a lot here which cannot be found in dozens of other series.

Sunrise apparently put so much effort into deg and executing the puzzles that they ran out of time and effort to do a good production job on the series. Oh, it hardly looks sloppy and does have some occasional good CG effects, but minor quality control slips and clunky-looking animation are regular occurrences. Kaito and Gammon get character designs which visually portray them as delinquents (one has to wonder how they can get away going to school dressed like that), while Nonoha and Cubik get bright-faced looks which make them appear to always be staring wide-eyed at things. Beyond Erena, other designs are decidedly ordinary; in fact the only place that the series impresses artistically is in the layout of the Root Gakuen campus, which would put many colleges to shame. Who wouldn't want to go to a school like that? Graphic content is minimal and fan service nearly non-existent.

May'n is a highly-charged, rockin' number which well sets the tone for the series, but closer “Hologram” is less remarkable.

The English Funimation dubs also experience this from time to time. The subtitles are fine except for one place where “Children” is used when it clearly should be “Puzzle” instead.

Sentai's Blu-Ray release (it is also available on DVD) has no significant problems in a transfer or video quality sense, but the content's artistry and animation are simply not sharp enough for it to look all that impressive, either. The DTS Master Audio 2.0 tracks for both languages are not top-caliber stereo mixes but work plenty good enough, with respectable fidelity and dynamic range on both tracks. The packaging takes the typical Sentai no-frills approach of two disks in a regular-sized case, and the on-disk Extras likewise follow suit by only providing clean opener and closer.

Phi-Brain can definitely be entertaining, especially if one has a penchant for puzzles. However, it is also quite capable of making its viewers cringe. Through its first 13 episodes it does the former more than the latter, and that, apparently, is enough to make it a hit show.