Mein campf is ... well, it's rambling. Think one of those internet "we didn't land on the moon, climate is bad, boo immigrants" texts rambling. The quran is rambling too, but of a different kind. "you must do X, you can't do Y, he must do Z, if you do A, B and C you'll be rewarded". It'd be fine, but it's 50 freaking pages of that. Why are you claiming "boring" is an unfair assessment of this ?
I'm unsure what the definition of pamphlet is, but the communist manifesto definitely exceeds what I'd consider length limits for pamphlets.
Trying to make some kind of comparison between Mein Kampf and the Quran (and by extension, the Torah and the Bible since they contain much the same content) is beyond idiotic. Have you really read either of the Quran and/or Mein Kampf?
The definition of a pamphlet is an unbound booklet, which is how the Manifesto was originally printed. It's length was 23 pages.
I'm unsure what the definition of pamphlet is, but the communist manifesto definitely exceeds what I'd consider length limits for pamphlets.