How does MITIE perform named entity recognition?
After having used MITIE for a few weeks, I feel like I at least have enough to answer my basic questions:


(and 3.) All models need to be trained from scratch - there is no online method to add new samples to the model as they come in. This is unfortunate because MITIE takes at least 45 minutes to an hour to train on a ~20k-sized dataset.
The datasets I used were ATIS, CoNLL 2003, and DBpedia


I've found MITIE to be quite good as far as classification accuracy goes, although it takes a bit of work to prepare datasets for it.