Disclosure: I'm the guy that made the updated White Box: Fantastic Medieval Adventure Game. I had no involvement with this book.
This is a fantastic supplement for White Box games. The New classes are flavorful and have easy mechanics, which is ideal for WB (keep it short and sweet). There is a new spell list for the Druid, instead of just using the cleric spells.
Check this new spell description:
This spell gives a chosen person immense strength – his muscle mass rips apart clothes
Just awesome. Every game needs a Hulk.
The feats may turn some people off, just by the name alone. But they are short and sweet (see the pattern?) and it adds a way to add more mechanical differentiation among classes. Some people will like that. And hey, you can always change the name!
The layout is clean and the art is really good. There are a few typos and grammar errors but I don't believe it's the authors native language.
All in all, I think it's a great little product for White Box games, especially at the PWYW price.