Maslin's wonderfully worded review finds much of the magic that made the original such a hit still in place. The positive assessment notes Brown's retention—and what some might even consider repurposing—of the characters, plot elements, twists, and underlying themes in both The Da Vinci Code and Angels & Demons. Also, that's he "bringing sexy back to a genre that had been left for dead," speaking of the genre he revived, killed with his books, and revived again with the new one: contemporary historical conspiracy theory fiction (not a technical name). Not surprising: Brown's Harry Potter for Grownups is a brand, a franchise, something that's been carefully, strenuously vetted, and they weren't going to release the new Dan Brown book as anything but a populist crowdpleaser. Good on 'em, and good on Maslin for seeing that.
I had a different take.
Basically, the long-haired skeezeball professor that Tom Hanks played with the weird wig comes back, and he has to fight another bad guy who's all tatted up except instead of being Christian, he's just tatted up, but he's still a weirdo that's involved in Freemasonry, which is more or less that frat George W. Bush was in when he was at Yale, but slightly different and older and crustier and they like to do whippits while molesting children! But that's only the first secret. Some of it takes place inside the Capital instead of the Lourve, which is different because there are a bunch of scary legislators and they're all in on the secret of being into pervy ritualism. The bad guy says hacky bad Magneto-like things ("If they only knew my power,""Tonight my transformation will be complete.") and has a bad hacky Magneto-like name ("Mal'akh"), but instead of being Magneto, he's just a character in a Dan Brown book who's weird and has no special powers but being especially creepy, which I guess is a power if you want to have a lifetime of awkward-turtle moments, and apparently the "capital" holds intense mysteries that nobody's ever seen before, like an extra bathroom to fondle pages in and places for John Ensign to sit and think about what he's done and for Jim Gibbons to practice punching out showgirls in the gym, and it's amazing. The secrets of American History are being slowly unwrapped, one by one, like individual sticks of gum! But in order to get into the room to fondle the pages and to wipe your ass with the same toilet paper that The Founders wiped their butts with, Professor Greasehair has to "swat bitches away with a stick" because they all loved his last book about the Mona Lisa postcards and the Goyim Albino who won't stop hitting himself with the anal beads. Once he's done making meta jokes about how awesome his last book was—which is basically Dan Brown being like, ha ha, I'm writing shitty books and I know it and the best part is you're still buying them, suckers—there are all of these codes, everywhere, and they hold the secret to the founders of America doing strange things and having strange sexual fetishes and get this, George Washington was Jesus and Jesus was black and they all were in the same frat at Yale before Yale even existed! Holy shit. Professor Paul Mitchell gets chased by The Awkward Turtle and has to figure out even more crossword puzzles and do lots of Sudoku before he's killed by TAT and it turns out the actual villain of the book is Will Shortz, he of the New York Times Crossword Puzzle fame, and if you do all the New York Times Crosswords that have ever existed, and take the fourth letter down and the fifth letter across from every one, they spell out where the treasure is, and supposedly, the treasure holds the used toilet paper of the founders that was saved, which is priceless. But nobody will ever be able to do that, because Will Shortz destroyed a bunch of the originals, except for that one copy, which is hidden deep within the caves of Sierra Leone in a bloodthirsty baby kangaroo's ass named Aaron Burr (the kangaroo, not the kangaroo's ass, and what's with all the asses?), and now, we can have a sequel where Bumble and Bumbling chase a kangaroo who IS A VAMPIRE that sparkles when he pees.
Oh: spoiler alert, I guess.