Despite its small size, this book is a great source of new material that can strengthen a Pathfinder campaign in many ways. Both players and DMs will find use in these mechanics.
Many of the skill uses are fairly obvious, but the designers did a great job adding depth to those ones. Kip up, the ability to stand up from prone quickly, is given an elegant treatment.
Many of the skills are especially useful for non-casters like the Fighter or Rogue. The treatments given to skills like Acrobatics, Climb, and Survival can sometimes tilt the balance, or at least lead characters to make interesting use of the terrain. While these skill uses will not close the gap between martial and caster classes, it does give non-casters more options, some of which are circumstantial, but very useful circumstantially (like the ability to temporarily curse a magic item through mundane means).
Of course, anybody can make use of these skills. Bards, clerics, wizards. Some classes might invest in skills they never considered after seeing the applications of new skill uses.
Some of the skill uses can add a lot of flavor to a game session. Use Heal to perform an autopsy or cover up a murder disguised as First Aid. Use Diplomacy to call for a cease fire or talk some sense into an opponent who has no cause to fight you.
Most, if not all, of the skill uses have consequences for failure. And where the skills are powerful, failure on those skill uses often have perilous consequences.
Some of the mechanics' phrasing is slightly awkward and several of the systems use a different mechanic than I would prefer. However, the mechanics are still suitable and a DM could intuit a more preferable system without changing the substance of the mechanic. Also, a small amount of the material does step on the toes of feats and class features, but they usually tread softly.
The book is well-formatted, searchable, and pretty. It suffers slightly for sometimes not separating its paragraphs well and it could have subdivided its bookmarks into individual skill uses. The artwork is good and varied, but not exceptional. Also, the artwork is meant to be illustrative of uses, but does not match remarkably well.
Because these skill uses are independent of each other, DMs can pick and choose what they want to allow in their campaigns. Wise choices can influence the overall feel of a campaign as players explore those options. However, almost all of the skills seem balanced, so there should not be much fuss about letting in the entire book. Of all the selections, I found only one (using Spellcraft to learn basically everything about a spellcaster) to be worrisome. A few, like that, stretch credibility for being mundane skills, but they are limited easily enough if a DM does not want to allow them - and they make great additions if you have an Epic Fantasy campaign.
The book's price tag, $5.99, is hefty for a 19-page book, even one as crunchy as this.
If you have the money to burn, this book is a good buy. It provides many interesting and useful new uses for skills, which can add a lot of fun, flavor, and feel to your Pathfinder campaign.
[5 of 5 Stars!]