The Bad. New feats are easy to screw up. It's often hard to translate a good idea into a concise mini-rule that works and is neither too complex nor too weak nor too powerful. These guys have made a valiant attempt to incorporate some GREAT ideas. But they have fallen short in making a GREAT set of feats. Rather they are kind of so-so on the whole. Two or three are useful and not available from UA articles.
The Good. The feat, Unyielding. Balanced, useful, and simple. Excellent! The others are great ideas but are either too complex, unbalanced, or excessively narrow. I would give specifics but I don't want to reveal any contents. Slight tweaking would make these much better. Overall? Certainly worth the .50 I paid. I've seen worse--keep plugging!

Some good ideas, some bad ones some complicated ones.

I like the premise of Racial Feats and some types of Weapon Mastery feats. I also like some explicit "Alchemy" definitions, but I feel like the feat is really trying to make up for an existing problem of missing rules.

I would probably allow about 35% to 50% of this material into my campaign, but for an inexpensive book, that's a fine ratio.

I evaluated these 21 feats for use in my campaign. 8 were approved. 9 were over-powered. 3 (Draconic Wings, Monster Hunter, and Navigator) I think can be made usable but aren't ready now. I rated Scabbard Duelist as too complex, and Alchemist as both OP and too complex.