These rules have helped one of my PCs play out a Dwarven blacksmith while still giving him time to adventure with the others. They PDF presents excellent guidelines to really "make craft work" with an adventuring party. At the cost of realism, it drastically cuts down the time it takes to craft some of the more "difficult" items in the rulebook, such as fullplate.
If you're looking for a good set of craft rules to go by, go for these. They've worked wonders in my campaign so far. Simple, elegant, easy to read, and short.
This is my favorite of the Undefeatable series (almost tied with the Barbarian one).
I've always thought that Sorcerers and Wizards were lacking in the amount of feats they had options to, and this really opens them up. They allow for great amounts of versatility and a lot of fun spell options. Nothing jumps out as being overpowered or abusable, and it seems like it would be easily added to any ongoing game.
I love most of the other Undefeatable PDFs, but this one was a miss for me. I find Fighter's are difficult to do, so I can't say I expected any less.
The feats in here seem a little flashy for my tastes: creating golden replicas of your weapon that strike with you on your next attack, opening rifts in the ground with your weapon, conjuring buffeting winds to encircle you with a swing of your blade, etc. They're just not hitting their mark for me. Though if you liked TOB:Bo9S, then this might be more for you!
The balance of some of these feats are questionable, and having a party full of powergamers means I have to really eyeball things before I throw it onto the table to be torn to shreds. The mount feats didn't particularly excite me either, but that's more of a personal bias than a legitimate concern; those feats themselves seem alright.
Overall, if you've purchased the other 4 PDFs, I would either, A) grab this for the collection, or B) skip it in favor of a better one.
I would say that these are some pretty enjoyable Barbarian feats, and none of them jump out as being particularly imbalanced (which is often the case with third party products). The only editing error I can see is that I'm not sure if the feat "Might Blows" was intentionally labeled as such, or if it was meant to be "Mighty Blows", but nonetheless it all seems quite cool.
The Animal Aspects are pretty cool, too, though I'm not sure if I'm sold on the Bear or Bull Aspects giving +8 to an ability score... that seems a little over the top.
Otherwise, I would suggest this to anyone interested in spicing up a barbarian in the party! Lots of cool things in this PDF.
I haven't had a chance to run most of these, but I threw a Canopic Jar in our session today, and let me say that it was well worth it - they're very cool, and quite possibly my favorite creatures in the volume.
The other monsters all look pretty interesting as well, and I'm looking forward to using most of them in future combats. The Riverwrath is gonna be my next target, since she looks fun with her waterspouts and whatnot.
All in all, a solid PDF for anyone looking for a few new creatures to keep the PCs on their toes! Even if you didn't like Tome of Secrets, don't let it sully Adamant's reputation on this one; there's a few editing errors, but nothing exponentially large enough to prevent you from understanding anything or playing it. Besides, its only 5 bucks!