Explanation for Why Logistic Regression can be so Accurate in Sentiment Classification?
Some people have this preconceived notion that logistic regression shouldn't perform well because it is too simple. While that might be true for certain types of complex problems, the reality is that logistic regression performs relatively well in many different scenarios.
It's difficult to give a definitive answer as to why a model performs well without actually seeing the data and the model you've constructed.
That being said, it could be that the problem you're trying to solve is not very difficult so even a simple logistic regression model yields good results. Another thing to consider is that while 88% accuracy sounds good, it might actually only be OK for this type of problem (and dataset) - it would be informative to try other non-neural-network based classifiers and see how well they perform.