To be written and expounded upon once there are enough books and people to actually write critiques....
Just some basic rules to follow:
Don't criticize the author; critiques need to be on single books/series.
Don't let your personal tastes or opinions overshadow the critique too much: a critique is a logical analysis of an argument, writing, or action. For this wiki, that means a logical analysis of a book. Look at why you think it works, why you think there were problems, why it might have fallen short of what you hoped for, or perhaps some of the holes in the plotline.
Yes, you may state that you enjoyed the book or series quite a lot. That isn't enough to qualify it as a critique, though. You need to bring an analysis to the table somewhere, bring in the content of the book itself. Without that, it's just an opinion blurb, which easily fits in to the comments.