I LOVE Lamott's essays/memoirs, which often make me laugh out loud and cry (sometimes simultaneously!) but I tend only to like her novels. Imperfect Birds is well written and important, and although ultimately hopeful, Rosie does an awful lot of drugs putting her mom through an awful lot of pain before there is any resolution. Lamott clearly "gets" the teen scene she is writing about. I care about the characters and had to read to find out what would happen, but the process wasn't always a pleasant one - kind of like life, I guess, which is one of her main points. On page 10 we get to hear her main theme, life is "often messy and cruel and dull, and we do the best we can. It's unfair, and jerks seem to win. But you fall in love with a few people."
I much prefer Lamott's essays and autobiographical books to her fiction. My favorite is still "Operating Instructions," As a parent of a teenager, I just found this book depressing and uncomfortable and very California-y...I did not enjoy it, but to be fair, the writing is good, characters are well-drawn and parts are witty. So you could make the argument that Lamott has been very successful in what she set out to do --