You might like books or not - but a year ago I started working with a company that should develop a system based on Elasticsearch, NodeJS and AngularJS instead of using LAMP.
At that time the first edition of the book was one of the first books covering Elasticsearch and it helped a lot to give the developers a quick start with ElasticSearch.
Many updates between 0.20 and 1.x made the first edition outdated - the second edition closes this gap now.
It covers new features like aggregations, percolation, snapshot repositories and provides in many places more details (e.g. handling geographical information). In addition it gives hints for the configuration e.g. where default settings have been changed (e.g in version 1.x the default setting for bulk index size is only 100 MB). Therefore I think the book is not only relevant for beginners, also for team leaders, which are not always in the details - but need an impression of features and initial hints for proper system configuration to be checked with the team - a really important issue because Elasticsearch is shipped in "development mode", and not in production ready configuration.
Thanks for efforts to update the book for such a dynamically changing system and providing this nice guide, for the next "generation" of users.