Sure you do, Wolf. You were disappointed and you have a right to feel that way. If you went to an ice cream parlor that was giving free pistachio ice cream and you thought you were getting pistachio ice cream but were served vanilla (which is still pretty good, but just not what you were expecting), you would have a right to feel “cheated” even if it was free. HOWEVER, in my humble opinion, you should not give VOICE to that disappointment to the person who gave the shiur etc, in view of the facts you stated regarding it being a free shiur, not being a member of that shul, etc. If you paid good money to attend the shiur, then you have a right to express your dissatisfaction.
