Secret Wars #1 was solicited by Marvel Comics as a 40 page comic for $4.99. You can usually knock off 12 pages for covers, ads, backmatter and “previously seen on Buffy The Vampire Slayer” intros to find the full comic book page count. So a 32 page Marvel comic gives you bout 20 pages and a 40 page comic gives you around 28 pages, which is how Secret Wars #1 was solicited at $4.99.
Well, it seems that someone wants to give you a bigger bank for your five bucks. So Secret Wars #1 will actually be 56 pages long, probably giving you around 44 pages of story. Which is pretty decent when you break it down.
Of course, this is a Jonathan Hickman comic. So there may be title pages, chapter breaks and varous symbols dancing around pages to help expand it a little. But as folks are now judging comic books by the amount they weigh, every gram counts!