Overall an improvement. There ARE some things I'm skeptical of or waiting to see in action - such as weapon mastery abilities (I'm a bit worried about there being too many sources of advantage / disadvantage, or that some of the weapon traits aren't worth the added complication); or the summoning changes. There were some wasted opportunities to clarify things in some cases. I hope they scale up Monsters and give them some extra options / abilities to make up for PC power creep.
My major issues with the book are formatting though - the spell lists for each class were put in the individual class descriptions rather than the beginning of the spell listings; making them harder to look up. They also COULD have included hanging tabs or clearer chapter labels to make flipping to individual sections easier. The glossary is an improvement over the 2014 PHB's index at least.