I had fun reading The Alchemyst, but it's far from my favorite fantasy story. Saying "all myth is based in fact", and then pulling characters and devices from all over the storybook map - historical-and-mentioned-in-Harry-Potter characters like Flamel, the Witch of Endor (Book of Samuel in Hebrew Scripture), Excaliber (Arthurian legends), Bastet (Egypt), Morrigan (vampire extraordinaire), nunchuks (every bad ninja movie ever made), Yggdrasill/World Tree (Celtic), etc. - seemed a forced attempt at creating a non-humorous Shrek-like fractured fairy tale world. And the pouty, jealousy-riddled sibling relationship between twins Josh and Sophie wears on the patience after awhile.
On the good side, I found Scott's description of the destruction of a shadow realm to be beautiful. Dr. John Dee is portrayed successfully as the quintessential villain, sulphorous/brimstone smells and all. And the adventure does reach fun, higher speeds at times. The Alchemyst is just good enough to make me want to continue on with The Secrets of the Immortal Nicholas Flamel series.