So, Chapter 1 features new races. We have living toys, plant folks, mousefolk, and ghost-like people. We also get a bunch of feats to use with the Variant Human option, to simulate things like half-dwarves and half-minotaurs.
Chapter 2 has new classes (some, but not all, of which are available individually on DriveThruRPG, though in some cases, those individual entries have things not featured here, like how the Complete Gunslinger has options for lasers and other sci-fi options, which are not featured in this book). Each class also features several subclasses. The new classes are Alchemist, Captain, Craftsman, Gunslinger, Investigator, Martyr, Necromancer, Warden, Warmage, and Witch. It seems very Pathfinder-esque, to me, as some of these seem like stuff you can do with the existing classes.
Chapter 3 looks at the base classes from 5e (barring the Artificer, as the Alchemist and Craftsman classes more or less supplant those). Each class gets six new subclasses. Some of the standouts include the Way Of The Mask (the aforementioned luchador subclass for monks), Circle Of The City (if you want to play Jack Hawskmoor from the Authority), the Toon Sorcerous background for Sorcerers, the GM Patron Warlock (to break the 4th Wall), the Way Of Streetfighting (HADOUKEN), and College Of Graffiti.
Chapter 4 has new options for customization, including how multiclassing works with the new classes presented here in.
Chapter 5 and 6 have new equipment and spells, respectively. We close things out with a few appendices, including variant rules, stats for new familiars (do you want your wizard to have a friendly flying book floating around? Now you can!), and rules for a in-universe game called Siegeball.
Scattered throughout the book are comments from Valda the Lich, many of which are quite humorous.
Overall, this is a fun book. Much like the Tales Of Arcana Race Guide, this book looks at trying to recreate a lot of popular culture for 5e, and that makes sense. Many players, especially newer and/ or younger players, are going to want to try and recreate their favorite characters from movies or TV for a game. So, if someone says āCan I play Winnie The Pooh if he were a wizardā, you can say āYESā.
Essentially, Valdaās Spire Of Secrets is a ton of fun and adds a lot of variety to 5e.