This is a dataset which contains amazon.com book reviews for the purpose of training a Sentiment Classifier. 
There are 213.335 book reviews for 8 different books. There are books which are scored very negatively in general and books which are scored very positively. 

Gone Girl: 41.974
The Girl on the Train: 37.139
The Fault in our Stars: 35.844
Fifty Shades of Grey: 32.977
Unbroken: 25.876
The hunger games: 24.027
The Goldfinch: 22.861
The Martian: 22.571

Each entry is separated by a newline character ('\n'). Each entry contains four attributes, which are separated by a space (' '):
1. review score
2. tail of review url (https://www.amazon.com+<tail>)
3. review title
4. HTML of review text 


website: http://ataspinar.com/2016/01/21/sentiment-analysis-with-bag-of-words/