Apologies for being a day late in posting my TT response. I have used LibraryThing's EarlyReviewer's program since I purchased my lifetime LT membership almost a year ago (LibraryThing is Most Awesome!). This is a great feature with the potential of winning books and also a reference for books about to be released. I only "Request" 1 or 2 books a month, sometimes none, as I already having a large TBR pile at home, and only those books that really interest me...and that I think I could win. So far I have won four books. Any given Doomsday by Lori Handeland which I DNF but posted about. The Sugar Queen by Sarah Addison Allen and The Wednesday Sister's by Meg Waite Clayton both of which I loved, reviewed and highly recommend. The last is Woman Of A Thousand Secrets by Barbara Wood which I have yet to read.
I like the fairness of the LT's ER program...determined by a variety of criteria including the books in your library, your reviewing history, random chance...much more fair than some arbitrary choice by the publisher as it gives everyone more of an equal oppourtunity...but I think you need to have books in your library that relate to the book you are requesting to have a better chance of winning.