The L.A. Times has chimed in with their review of The Lost Symbol (warning: some plot elements discussed), and overall seem impressed - though...

...it's hard to imagine anyone, after reading "The Lost Symbol," debating about Freemasonry in Washington, D.C., the way people did Brown's radical vision of Jesus and Mary Magdalene in "Code." That book hit a deep cultural nerve for obvious reasons; "The Lost Symbol" is more like the experience on any roller coaster -- thrilling, entertaining and then it's over.

I'm sure the reviews will start coming thick and fast now, so maybe best to just pick the book up tomorrow and read it ourselves!