As with most of the Oz tomes after the first few, the plot is slight, but the younger kids will enjoy it well enough, and the inventiveness of the creatures and countries surrounding Oz are still fun.
There are a number of inconsistencies, and the reliance on magical travel makes things too easy for the characters, but that's an old problem and won't bother the children too much.

There is a passing reference (p. 16) to a once-common but now eschewed term for Native Americans, in the context of watching a program on the then-amazing-and-new television device, but that is the only problematical word in the book (or indeed in most of the Oz volumes).

(Dates are for my latest reading.) ( )