But apprently, as I heard the man behind me comment, so was the book, The Life and Opinions of Tristam Shandy, Gentleman , by Laurence Sterne (Late 1760's).
I swear I heard Nino Rota's 8 1/2 score running through any scene that had to do with the carnival, and the direct parallel (if I'm not imagining the score) is apt. Only rather than 3 layers of narration, I'd guess Tristan Shady: A Cock and Bull Story, had about 5. It was so convoluted one stopped trying to make sense of it all, and just focussed on each moment as comedic in of itself. Parts were very funny, and the audiance laughed out loud. Other parts seemed random, or out of sinc with the general flow (all the over-the-top womb scenes, come to mind).
So, its pretty fun and entertaining if one doesn't know the book. Which includes me, and I'd give it a B/B+. If one does know the original writing, this film might border on genius (as the man behind me seemed to think it captured the spirit of the prose perfectly). If you do know the novel, by all means I'd love to hear your take on it, and its film adaptation.