When Neuro obtains the office is where the story gets interesting (so stick with it until then), after that you are gripped by suspense and witness many clever ways of killing a person, the science behind the puzzle become very complicated and intriguing later on.
The only OTHER bad side of this manga is that some adored supporting characters will die (I won't say much so as to not give it away) and that can piss you off a bit. And might I add that a lot of the deaths are caused by the interwoven fates of all the other characters. ALL background story is actually prevelent to the advancement of the story, so pay close attention.
So, I suggest you stick with it in the beginning, you won't regret the time you spent.
