Bloody Monday begins and it's 'good'. It's not bad. It's worth reading, but it isn't awesome.
But then, THEN it picks up momentum. And right now (volume 9) it's so ridiculously good, you can't pass on this.
There's plenty of action and suspense, and you actually come to care about some of the characters (Fujimaru though? Not so much. He's a bit carefree, doesn't have much of a deep past.) including the antagonists. In general, it isn't just a mindless read, there are many elements that are thought-provoking, you wonder 'how' or 'why' or 'what'. And it isn't an emotionless read either, there's certainly the emotional element (but that doesn't mean we're talking about the weak emotions - it's not some sappy romantic shoujo). It should be mentioned that at the beginning there seemed to be some romantic potential, and it's a little misleading, since the plot goes nowhere near it from then on. It should also be mentioned, while we're on the topic, that this manga is full of fine ass.
This manga has excellent art and story and... framing, I suppose you could put it. It's not just that the artist draws well. It's what he draws, the perspectives, the expressions, the tone and mood, and the settings. They're just spot-on.
At times, all the technobabble feels like a bit of a gimmick. And I suppose it is; the protagonist has to be good at something. And the plot is rather technology-centric as it's set in the modern day[?]. Another 'gimmick' the manga has is the 'psychological explanation' element, the manipulation of people based on their tendencies and such, but then that's always interesting to me and it doesn't feel as much like a gimmick.
Also, the protagonist is rather a moron, but he has his moments. There was one point in the story where I absolutely hated his guts because he was just that pathetic. He's since redeemed himself in my eyes.
But you'll just have to read it to believe it.