Unsatisfying
Part of speech: adjective
Definition: Not providing satisfaction.
Disappointing
Part of speech: adjective
Definition: That disappoints or disappoint.
Part of speech: verb
Definition: To sadden or displease (someone) by underperforming, or by not delivering something promised or hoped for.
Example sentence: The more time passes in your life, I think the greater you understand perspective. So I'm happy that I've had experiences that have reminded me that most exciting things might not feel so exciting later, and the most disappointing things might not be so disappointing later, either.