One of the biggest issues is that the plot and the way characters act just make no sense. Oftentimes nonsensical things just seem to be normal to characters and don't require more examining. The puzzles themselves oftentimes don't make any sense either and I have no idea how the character draws conclusions sometimes. It feels like a very sloppily thrown-together show that someone with no concept of good storytelling wrote.
The characters are very bland and flat. The main character is so well-loved for absolutely no reason whatsoever.
The OST does not stand out at all (oftentimes it's some vocal song that's probably the ending theme?), and I found the opening theme to be bad, in terms of both vocals and how it matches the music.
The art is strange - character designs do not stand out, and some of the drawings (especially of muscular men) are really weird. Additionally, characters oftentimes have a really heavy outline and stare right at the camera when talking, so it seems like one of those visual novels/video games. This is further compounded with the contrast between the not-very-good CGI (?) background and the animated characters. There's also a ton of repetition in terms of reusing footage - which would be okay if it was a longer anime, but if 1/5 of each episode is the same footage (transforming sequence, Q-Stone sequence) then it gets bland really fast.
Overall, everything is just not good - story that makes absolutely no sense and characters act nonsensically, music and art do not stand out either (which sometimes, for me, are somewhat redeeming factors).
