If your book covers a hot topic of today such as politics, abortion, sexual abuse, recession, etc., giving them away to key people might be the best way to sell them. There's no denying that giveaways present opportunities to have your book noticed and read by people who might not ordinarily pick it up.
A book review is a valuable piece of your media kit. Valid reviews present a picture to readers about the benefits of having and reading your book. Without reviews, readers can only assume one of a couple of things: either the reviews you received were too bad to print, or that you are new to the publishing industry. Either of those choices means the reader will quite possibly go on to another book. Give some, sell some should be your motto.