This contains a new expert path (the Knight) along with some small edits/buffs to the Berserker, Fighter, and Ranger form the core Rulebook. The buffs to the Fighter are especially important- the Fighter was probably the weakest of the core rulebook expert paths, so it's nice to see it brought up to speed with the rest. The Knight is a great addition, it provides some strong defensive options that had been missing from the Expert Paths.

That being said, Robert Schwalb has already said that the updates to the core classes wil be added to the core rulebook at some point, so it's personal preference whether this is worth it for the Knight and the information on the buffs right now.

You get what it advertises: upgrades for the Berserker (minor), Fighter (significant), and Ranger (minor) along with the all-new Knight. The Knight fills a slot that the Paladin never quite did (IMO), and the upgrades to the Fighter make it a truly stand out choice for a warrior. I still wish it offered a bit more, but it's a good value for the price.