Don't be fooled, this manga is full of flaws.
Don't get discouraged, this manga is full of epic moments.
Don't get too excited, you can write everything that happens in this manga in such a way that it becomes obvious how formulaic it was.

Infinitely better than Monster, though, and I say that really being objective.
20th Century Boys has a lot of nonsense that's there to lead to great payoffs. Monster has nonsense that leads nowhere.

I remember this manga especially because of this:
-You anounce what you are going to do
-You go ahead and do it
-Everybody who heard you the first time is still very surprised because you did it to perfection, or in such a way that you turned it on its head while remaining true to your initial announcement.

It's hard to put that in a better way without spoilers.
Bottomline, it's a nice manga with great moments that maybe didn't deserve the goosebumps I got when I read them, but goosebumps I got nontheless.