I can now officially report the book's quality never wavers, start to finish. Any worry there'd be a sag at the 3/4 point (my complaint with a huge number of contemporary books) was completely unfounded, and in fact the 3/4 point was every bit as exciting as all the other quarters.
Lionel Essrog is one of the most inspired characters in contemporary fiction. I'll go ahead and put that out there. His determination in the face of his challenges is inspirational, and even if it was completely impossible for me not to laugh at many of his outbursts, that didn't diminish the respect I had for his character. Rather, it endeared him to me even more. Jonathan Lethem had me completely in the palm of his hand the whole way through, and Lionel is probably the biggest reason he was able to achieve that feat so easily.
Motherless Brooklyn reminded me, in some ways, of the Curious Incident of the Dog in the Night-Time. In both books a heavily challenged person is attempting to solve a mystery. I enjoyed both books, which probably says a lot about my love of characters who overcome physical/mental obstacles by sheer force of will in order to accomplish their goals. I enjoy these characters largely because their complexity ensures a surprise around every turn. As a reader, that keeps me on my toes and interested, and both Jonathan Lethem and Mark Haddon have the knack for creating just such a character.
So, that's Book # 3 for me, Motherless Brooklyn by Jonathan Lethem. And I really have to give it the full Five Blue Stars.