Four years after completing the Bartimaeus Trilogy, Jonathan Stroud returns with a prequel set in the same setting. The Ring of Solomon is set several thousand years before the quasi-Victorian era of the previous books. The sarcastic djinni Bartimaeus is enslaved in an era best described as "Biblical".
For those unfamiliar with Stroud's world, The Ring of Solomon serves as an excellent introduction. Djinn (or 'demons') are summoned and enslaved by magicians. They're not very happy about it, but, generally speaking, don't have much control over things.
Bartimaeus is one of the djinn. Even counting for his unusually inflated ego, he's smarter than most - and certainly more troublesome.
The mighty King Solomon rules the known world, aided by a cabal of magicians, his horde of summoned 'demons' and, of course, the vast powers of the titular ring. His wisdom and power are both vast, but not so vast that he can stop all the plotting and scheming amongst his many minions. Bartimaeus, with his magical ability to be in the wrong place at the wrong time, gets caught right in the midst of it all: assassins, coups and (even more) ancient sorceries.
Those familiar with the original trilogy will find comfort in many of the same elements that made it such a success. Bartimaeus is, of course, the hero and the source of greatest enjoyment. He's sarcastic, hilarious, informative and surprisingly adorable. The young Asmira, the well-meaning teenage heroine, is dull in comparison, as are the other human members of the book's cast (except the villain, a scenery-chewing Egyptian necromancer). The plot is predictable, as are its various twists and turns, but each individual scene is a hoot - capped off with one of the best chases I've read in genre fictions.
Although The Ring of Solomon is head and shoulders above the other young adult fiction I've read recently, comparisons against the original trilogy are inevitable. Bartimaeus goes through exactly the same sort of character development (which oddly belies his progression in the trilogy) and the plot is very similar. Due to the length - a single volume instead of three - The Ring of Solomon is less involved and less detailed. It doesn't muster the same depth as the original series and, as such, feels like a watered down version. (An interesting, if tangential, comparison would be KJ Parker's The Folding Knife as compared to his/her Engineer trilogy.)
Overall, The Ring of Solomon is an excellent introduction to Stroud's work and his world. Although enjoyable in its own right, hopefully it leads even more readers back to the ground-breaking original series.