How to implement multi class classifier for a set of sentences?
I was thinking if Apriori might be more suited for your purpose.

For your consideration:
1) Tokenize the training sentences into bag of words:
Review Sentence | Upside | Calm | Swimming | Cat

2) Tag the correct consequents for bag of words.

3) Apriori should produce 1 rule for ambiance and 1 rule for Entertainment.

Hope this helps.