Reviews are a mixed bag! Do you need them? Maybe, maybe not. BUT, one bad review can throw your whole mental state into a tizzy and cancel out any good ones if you let it!...That's assuming you got some good reviews...Either way, in the long run they really don't mean much...Sales do...and good sales mean the buying public liked your book well enough! 

Carrie Vaughn, author of the Kitty werewolf series, offers this about reviews in a post on the GENREALTY blog:

I’ve got two books coming out over the next month, which means a lot of reviews are going to start rolling in.  I’ve already gotten
one fabulous review.  But I’m bracing for the not-fabulous ones.

When my third book came out, I stopped reading the reviews on Amazon.  For the first two books it was exciting — holy cow, people are reading my books!  But then it got. . .weird, I guess.  There were just too many and they were too scattered to draw any conclusions from.  They were affecting my mood, when there was no reason they should be.

Really, I ought to stop reading reviews entirely.  The thing I hate about reviews:  it doesn’t matter how many people tell me they love the book, how many great glowing reviews it gets, it only takes one bad review to wipe all that out of my memory.

I don’t search for reviews any more, but people send them to me, and I feel obliged to read them.  Then there are the e-mails — 99.9% of them are great.  But every now and then one arrives that isn’t.  I’ve only ever written a couple of fan letters in my life — it takes effort and a bit of courage to write fan mail, I think.  So I don’t at all understand why someone would take the time and effort to write a personal e-mail to an author telling them what they hated about a particular book.  But it happens.  And it kinda sucks to get a letter like that.  That one overshadows all the positive ones.

I could look at it on the bright side:  my book really affected someone.  That’s good, right?  But one bad e-mail, review, or blog comment, can ruin my day.  I really need to figure out how to not let things like that ruin my day.  Focus on the positive, not the negative.  Which is easier said than done.

Also, I think about this, which I got from Neil Gaiman’s journal:

“… never take seriously anyone telling you you’re the best author who ever lived, because if you do you’d have to take seriously the person who announces that you’re the worst author who ever lived.”

See?  The good reviews and bad reviews end up canceling each other out, and I’m left feeling totally aimless.

Which I think means what I need to not read reviews at all and just concentrate on writing the next book.