It struck me as akin to calling an author on the phone and saying, “Hi, I reviewed your book!” and then hanging up. Which is how I phrased it to a friend later that day, who replied with, “And what would be wrong with that?”
I wished I had more of an answer than, “I don’t know … but something.”
I don't generally do it, but more because I'm lazy (my blog is set up to auto-tweet whenever I post) than because I have strong feelings about the practice. I have noticed, though, that Kirkus will sometimes include an author's handle when tweeting my columns, but only (hopefully?) if I had a positive reaction to the book. (Otherwise, it would be a little bit like, "Hey, you! Yeah, you right there! LEILA HATED YOUR BOOK!" Which would be mean.)
I do see his point about it seeming "chummy", but couldn't that be said of any social interaction between authors and reviewers?
At the same time, when I LOOOOOOOOOOOOOOOVE a book, I oftentimes will tweet the author and tell them that. Because sometimes, I just want to thank someone for writing an awesome book. So I don't know if I think that's any more or less "chummy" than telling them such at BookExpo or wherever.
What say you?