"Unsatisfying" is an adjective in function. Its antonym, "satisfying", is also the present participle of the verb "satisfy", but "unsatisfy" is not normally used as a verb.
I was unsatisfied with the waiter's behavior
I am unsatisfied by your question.
It effected some economy, but some rude citizens who are unsatisfied with Obama's good-doings didn't allow children ,schools , businesses, or jobs to watch this national speech.
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
what part of speech is beneath
adverb
The part of speech for "explicit" is an adjective.
The part of speech for "lecturer" is a noun.
The part of speech for "rapid" is an adjective.
The part of speech of "came" is a verb.