In theory, the end of this adventure should be fantastic, but the confused story that leads up to it sinks this adventure. Entirely too many WTF moments, and motivations and decisions that don't make sense and that contradict existing lore. The lack of a proper description of the personality of the main NPC is a massive oversight. Not recommended.
The Moonscar is set on Golarion's moon, and - as expected - takes a dark approach to the setting, with the part of the moon being described being an Abyssal blight on the moon, inhabited by a Queen of Succubi and her court. As the adventure starts, a gate has been opened between the earth and the moon, and the Queen is sending her minions through to kidnap important people, whom she will brainwash and send back as her slaves.
Unfortunately, although the adventure does a good job of describing the Shrine of the Queen, it does a much poorer job of describing the moon's surface; a lot of potential is wasted here with the wilderness section basically just being combat encounters. You could very easily transplant the adventure to the Abyss and lose nothing.
The adventure is combat-heavy with a few tricks and traps, and although there are some role-playing opportunities, they don't rise to the level of Richard Pett's best works.
As an introduction to the Council of Thieves AP, this adventure fails to impress. The first section is "have random encounters until you get bored", and the final section is terribly short. There are good ideas here, but they are buried by horrible writing and editing. It took our group of five players about 5 hours to play through the entire thing.
There are some delightful moments in "The Midnight Mirror", but the ordering of the investigation material and the decision to leave out the statblock of a custom creature (especially from non-core material) baffle me. In addition, the adventure requires a DC 25 Knowledge check to defeat the final encounter, otherwise all has been in vain. For such key knowledge, why not make sure the PCs have it?
The best part of the adventure are the NPCs found in the final section, who can provide the PCs with a real moral dilemma as to what to do. A good GM can correct the problems with this adventure ahead of time, but they shouldn't have to.