The book opens the door to Hadoop world and guides you to major places such as HDFS, Map Reduce, Hive, Pig, ZooKeeper, HBase, Sqoop. Not only gives a first impression of what Hadoop, it also gives a deeper knowledge about each component and related technologies. Thus, if you just want a book to rule them all, pick this one.
However, because the ambition of the author is to put all into one book, you might feel overwhelmed with many details under the hood. It should be better you just read the introduction of a technology such as what it is, how it works rather than unraveling everything in this introductory book. Of course you might find it fascinating someway. Say, I was really interested in Map Reduce, HDFS and Pig and really enjoyed, but got bored with Hive and Squoop with many details. I'd rather pick other books that exclusively written for that technology.
There is also a disappointment about ZooKeeper. Actually, I excitingly read this part first for my assignment with distributed computing, yet it didn't help much. Neither it mentions streaming technologies like Storm, maybe the next version will include.
However the book was written so well with many deep understandings about the platform. It is definitely worth your time to read.
I put 5 stars.