GameMastery Guide -- Anything There?

[Palanan]

Is there anything worth reading in the GameMastery Guide?

I grew heartily tired of the bland pablum in most of the 3.5 books, so I'm leery of devoting time to what might be just another padded volume. But Pathfinder feels fresh enough I'm tempted nonetheless. Are there any genuine insights here, or anything else worthwhile?

[Drelua]

I've never found it to be too useful, but then I've never looked at it too closely. If you're running a very low optimization game and don't feel like building NPCs, the stat blocks can be useful. They are maddeningly poorly built, so they probably wouldn't work very well against a remotely optimized group though.

[Arutema]

It's mostly advice to GMs, wordbuilding and NPC and encounter design tips. If you're already an experienced 3.5 GM, not much to see here. There's a few rules subsystems such as chases, drug addiction, and haunts that are generally not all that well done. Haunts in particular tend towards "The Cleric wins initiative or you all suffer X effect." As clerics are not know for good initiative.... Chase scenes are a way to let a skillmonkey showboat for a while on a solo adventure because the rest of the party isn't going to make the checks to keep up.

There are pre-made NPCs, but the NPC codex has more of them if you don't like making your own NPCs.

In short, if you want new subsystems, Ultimate Campaign does better, if you want pre-made NPCs, NPC Codex does better.

[Psyren]

If only the skillmonkey can make it through a chase scene you're building it wrong, plain and simple. Chase scenes can rely on other kinds of checks too, like saving throws and ability checks. For example, the barbarian could find a shortcut by bending a hole in a wrought-iron fence with a Strength check, and the Paladin could spend a round summoning his mount yet regain the lost ground through Ride checks and possibly saving throws.

In short, in a well-built chase scene everyone should have a way to shine, with only the dice themselves determining success or failure - as it should be.

[BWR]

The GMG is mostly geared toward new GMs, so there's a lot of that sort of information there: how to prep, how to run games, rules adjudication, game problems, problem players, location, house rules, adventure crafting, world building, tech levels, different flavors of game, etc. etc.etc.
There's also some slightly more practical stuff like adventure hooks, random NPCs (both stats and names/personality), random ship names, tavern names, city locations, random encounter tables, insanity rules, and more.
If you are mostly interested in crunch oor setting fluff and are a fairly experienced GM from before, you don't really need it, but even having played 20+ years I found the book fun and occasionally helpful. If nothing else, it's a fun read.

[Psyren]

It's not quite as meaty as DMG2 but serves a similar function - DM techniques rather than just DM mechanics.