Lucky people that get to read books before they're released to the public, with the intent of finding what (tenative) public opinion will be.
Close, but more accurately, we are like beta testers. Most authors have a small circle that reads their work, to find any contradictions, holes, logic flaws, missing text (as in, the author thought he did something, but never actually stated it), etc. Jim has taken this, with Iago's help, to new heights. It's brilliant.
Also, bear something in mind...while we read the chapters before you guys, YOU get to read them at your own pace. You don't have to stop at the end of every chapter and wait.