With the philosophical themes involved, you read on, anticipating an ending that'll knock your socks off and leave you thinking about the character motivations and choices. Y'know, like Death Note. Because it's from the guys who made Death Note. That's probably the only reason anyone would go out of their way to read this.
The characters are a fairly dull lot. For the majority of the manga, they act like they're in a haze; devoid of emotion or ambition, they just kinda suffer along for the ride. The main characters always have this dead look in their eyes, too. They did kinda give up the will to live, so it's not too surprising, I guess, but there's nothing particularly interesting to recall about the characters. They become Power Rangers for some reason, the most interesting villain gets defeated, then we get a new villain who should be way more interesting, but he's not.
The commentary on society and religion ends up being way too forward and preachy; the manga doesn't really give you much to think about. By the end, each candidate tells the world what they will do as the new god; they each say something confidently and a little out of character, each one summing up a different ideal. It feels pretty cheesy that there's no overlap and that they're all such different extremes. How did this group of people ever cooperate this long?
Anyway, I'd say it's reasonably interesting up until the first big villain dies. After that, it's just very pretentious and fails to deliver. There are some decent little twists and turns here and there, but nothing incredibly outstanding.