Like clockwork, John Siracusa has assembled yet another epic Mac OS X review. You likely have read it by now, but still I kind of feel obligated to link to it out of respect if nothing else.
To give you an idea of how involved this review really is, I'll just note that it weighs in at ~27,000 words, which is, depending on various settings, 100+ printed pages.
Though I've Instapaper'd 15+ reviews of Lion, John's is the only one I have read (or will read) cover to cover. I'll skim the others, if that.