We use 10-fold cross-validation, and only two types of features: n-grams and Word2Vec word embeddings.  The n-gram features include unigrams, bigrams, and trigrams, including sequences of punctuation (for example, ellipses or "!!!"), and emoticons. We use GoogleNews Word2Vec features BIBREF28 . 
 Question: What simple features are used?
unigrams, bigrams, and trigrams, including sequences of punctuation Word2Vec word embeddings