When you're sad because something wasn't as good as you hoped or expected, you can say that you were "disappointed":

I was disappointed because I had hoped we'd get a chance to meet him.

We say we are “disappointed with” something (not someone):

I was disappointed with the new version.

 And you can say that you're "disappointed in" a person:

They're probably disappointed in me.

Remember that you use "___ed" to talk about how you feel:

I was kind of disappointed.

And you use "___ing" to give your opinion of something:

It (the movie) was kind of disappointing.

Other words that work in this way are:

• I was intimidated / It was intimidating
• I was surprised / It was surprising