I remember seeing Lost+Brain a few years ago and bookmarking it because the plot summary was interesting. After reading it years later, the only thing I felt about it is that it had a lot of unfulfilled potential.

The main thing about this manga is the comparison to Death Note and they are plentiful to see like the art style, main characters being geniuses, some of the plot elements and motivations for why the main character does what he does, but it's done in a way less interesting way, by an inferior cast of characters. The characters were just bland with no charisma. The two sidekicks to Ren have almost no characterization to them except that one is smart (he almost never shows it) and the other was helped by Ren's hypnosis and becomes obsessed with him (Like Misa from Death Note). Ren on the other hand is just a genius that wants to control the world with his motivation being introduced half way though the manga. Our other main character Itsuki is less of a bland character but it's not by a lot. He tries to stop Ren, but is always one step behind and for most of the manga it feels like he is following him from behind, rather than stopping his plots. His niece Yuki is not anything to write home about either. The other characters are basically useless and do nothing.

The story at it's base is interesting with hypnosis and what power it has to control an individual, and a lot of techniques are explored which helps the reader understand hypnosis better. Also I have my personal feeling that there is a subplot with how television can brainwash into believing everything they say without questioning it, as it is the way Ren uses it to achieve his goals, but I may be reaching here. The main problem I have with the story is again with the characters, as without any interesting characters the story gets dragged down and I can't begin to care if either Ren or Itsuki succeeds in their goals.
The art is decent, but it not anything special. It does it's job, it's clean there isn't anything more to say about.
In the end the manga isn't a disaster and because of it's short length you can read it in a day. If you are a Death Note fan and want to read something that has a similar plot and similiar MC (or straight up rip-offs) you may find something good in it, but it won't be something that you will remember.

This is my first review, so if you have constructive criticism I would love to hear it.