Hype: Help or Hinderance?

Next week, my most highly-anticipated book of the year will be released.  The Unbecoming of Mara Dyer.  The description sounds great, and the cover is even better.  You can't help but know this book is coming because its cover image is EVERYWHERE.  There are animated countdown widgets:
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Fan-made Mara Monday banners.
T-shirts. I loved the cover-art so much, I even bought a phone cover from the same line of photographs.
So yeah, there's been some serious marketing clout behind this novel, both from the publisher and on a grass-roots level.  And certainly, the initial sales will probably spike following next week's release (I know I've already got it pre-ordered for my Kindle).

But what I wonder is, after the initial purchasing tsunami, will all the hype help or hurt the book?  And what I mean is, I've built this book up so much in my mind based on the hype and so-far glowing reviews, that if it doesn't absolutely blow me out of the water, I'll be disappointed.

And I know this has happened to me for other books: like how excited I was to get my hands on Meg Cabot's Abandoned and then only felt luke-warm about it.  I wonder if I would've felt differently about it -- and given it a better review -- if I wasn't so convinced going into the book that it was going to be simply amazing.

For now, I'm staying optimistic about Mara Dyer.  There's no going back for me.  But in the back of my mind, I'm still a little worried.  Will my opinion of the novel live up to the impossibly-high expectations that I've built for it?

Does this ever happen to you?  Do you think a book can receive too much hype?  Or is all publicity good publicity?