According to me, some of the best features of the APIs are:
1. Gain meaningful insights, even from highly unstructured data.
2. Good accuracy.
3. A variety of ways to analyze text, like sentiment analysis(my personal favourite), emotion detection and sarcasm detection.
4. You can use their demo to test the APIs yourself.
5. Ease of creating an account, and the fact that the APIs are free to use. Review collected by and hosted on G2.com.
As such, I did not dislike any feature of their APIs. Review collected by and hosted on G2.com.