I preorder games I know I am going to enjoy.
I am an impulse buyer anyway, and I have a good idea whether I will enjoy something or not.
Right now I have Dishonoured 2, MGSV, Assassins Creed: Syndicate, and Fallout 4 on preorder, all because I know I will enjoy those games. I have ordered them all for PS4 too, as then I know my machine will handle it. In terms of reviews? I am not really bothered. These are all sequels to games I enjoyed, and watching trailers I know I am getting more of the same.
I will read the reviews of course, but I know they will all get good ones.
You don't tend to see many preorder bonuses (that are actually significant) of games without an established fanbase. Maybe a skin change or 2, or an extra challenge map here or there, but no extra sections.