To properly rate this book, I need a half-star between "it was ok" and "i liked it". I generally admire writers of-color who endeavor to rewrite "classics" and "greats," so that kept my interest, more structurally than on the level of actual prose style. Smith is no stylist, and, media hype notwithstanding, is no heir of Forster's on that score.
The most enduring, complex, memorable characters, for me, are the wives of the feuding husbands. Smith's great strength is in humorously, and sometimes quite painfully, rendering the alienation between family members. Overall, both families' dysfunctions were delicately wrought, especially across generations.
Generally, as with all of her work thus far, it was too long. I found the syntax and idiomatic slippages between British and American Englishes fascinating at best, and just annoying, usually. Smith is unquestionably talented, but my major complaint is less with her than with whomever the person is who claims to have edited her. I also take issue with her insistence on using her giant mainstream press power to publicly slam small, innovative/experimental/avant-garde presses and online journals by name. Gratuitous.
In the end, I read the book immediately only because I took a suggestion teach it in my "Other Tongues" literary class this spring 2009, though my aims might have been better served with Paul Beatty's White Boy Shuffle, saving this for a future "Adaptations, Revisions and Recursions" course.
I wish I had the time to read Howard's End first.