Here are the reasons why:
1. Sometimes, authors are so appreciative they do a reciprocal review of one of your books, and then share them with their own readers and fans.
2. It fosters good will among authors, and can lead to extra promotion.
3. It gives you something to blog about. That’s huge in my opinion, as there is nothing worse than staring at a blank screen and not knowing what to write. If you’re writing a review of a book you read recently, it’s easy!
4. It gives you something to share with your readers and fans so you’re not always in promotion mode, which can be a turn off for said readers, and fans.
5. It brings new visitors to your blog and could introduce them to your books as well.
There are of course other reasons to review your fellow authors books such as it’s important to read what others are writing in your genre so you can stay in touch with trends. And of course, there is the fact that reading is just plain fun and relaxing and we all need a break from writing. So, if you’re not reviewing the books you read, you should be, for all of the reasons listed above.