Sisterhood Everlasting (aka, the fifth book) SPOILERS

I heard about the fifth book coming out a few weeks ago, and was pretty psyched about the concept of seeing where our girls would be ten years after the last book.
I just finished it, and now wish that I could've left them there in Greece, coming to grips with the missing pants. I'm not saying that the book isn't good, but, to be honest, I'm glad I only waited a few weeks for it, as opposed to people who were hoping for a fifth book for years. It would NOT have been worth the wait- at least not for me.
This book was pretty much a total disappointment for me, right from the start. Lena hasn't grown at all in the last ten years as she still lives a quiet little life crippled by her overanalyzation and doubt (and love for Kostos); Bridget is unable to keep herself in one place for more than a few months, and her saint-like boyfriend, Eric, puts up with it, even when she runs off without an explanation to live on the streets; and Carmen, well, she's become a stereotypical New Yorker, obsessed with her iPhone (she wonders at one point what people did before the iPhone was invented after it broke down. I kind of wanted to shake her and say, "They survived. For THOUSANDS of years, people survived without iPhones. Imagine that."), dieting, and social engagements pressed upon her by her fiance who, in my opinion, she doesn't even LIKE that much, much less love.
As for Tibby, well, we never get to SEE Tibby, because Tibby gets the shaft in the worst possible way. Not only do we lose her in this book (EARLY) after a brief summary of her leaving the US for Australia two years before, we are robbed of her very presence entirely, save for a few letters that she wrote in the event of her death, which was rather convenient considering she died right before they all reunited in Greece.(So...WHY write letters when the reunion was planned in which everything- especially her long absence and general lack of correspondance- would presumably be explained? I'm sorry, but that just seemed like a thoughtless plothole devised soley to be able to hear from Tibby from beyond the grave, just when we thought we lost her for good, and thus manipulate our emotions.)
Most of the book involves, well, very little after that. The girls are lost without their friend, obviously, but then spend the rest of the book (right up until the last chapter) apart, not even speaking, and we are thrust into problems that should've been solved four books ago (Lena's indecision over Kostos and Bridget's restlessness, for example. Carmen, well, her storyline seems pretty pointless to me, and I found myself greatly disliking what 30- and a new life as an actress- has done to her.)
I suppose I'm so disappointed because I truly wanted to believe that these girls would stay friends forever, and while that may be true on a metaphysical level, one of them is gone, and everyone (including the readers, most of whom will no doubt be fans of the previous four books even than the movies) suffers for it. I feel cheated by Miss Brashares, who (IMHO) thought it appropriate to bring back the girls just to make them suffer. I understand that death is a natural part of life, but in this case, death seemed like an easy way out to me, especially when there are so many life tragedies that could've affected them and helped them grow and ultimately find their own happiness. There could've been drama to this book without having to resort to tragedy.
I've rambled on enough. PLEASE know that I am not trolling- I am more or less letting off steam, and hope that nobody minds. I'm just protective of these characters, I suppose, as I've come to see them as friends (even in just a literary sense).