I have used NLTK extensively to ace Machine Learning Hackathons
What do you like best?
NLTK has plethora of tools to clean and pre-process your text data. I cannot imagine how many hours it would take to sit and manually clean the text data if it wasn't the amazing in-built of NLTK. I would say NLTK has made life of Data Scientists easy.
What do you dislike?
Some of the functionalities like Lemmatization is pretty slow when corpus size is large. So, I have to adjust with stemming. Also, spelling correction functionality doesn't perform that well for SMS language. It would be amazing if the support is extended to identify the words in their short-form.
What problems are you solving with the product? What benefits have you realized?
I have used this library primarily for text cleaning in the pre-processing stage and feature extraction before building ML model. While working on Hackathon problems, I tend to experiment with various functionalities of NLTK toolkit for effective processing of the text data. The best part is most of these tools offered by NLTK is quiet easy to implement, mostly can be achieved with a single line of code. Whenever I am stuck, I refer the official NLTK website and public forums and I always able to find the workaround.