Fun is sometimes used as an adjective in the following contexts:
It was a fun thing to do.
It was a fun place to go to.
She is a fun person to be with.
She is fun to be with.
It was fun to go there.
It was fun to do that.
Fun here means pleasant and enjoyable. It/she made you feel happy.
However, funny is the normal adjective and fun is normally used as a noun. Note that when funny is used as an adjective in this way, it will have one of two quite different meanings. Consider the following:
She is a funny person. She makes me laugh.
She is a funny person. Her behaviour is really strange.
Adjectives describe the qualities of people, things and places. They are one of the largest word classes in English. They are normally placed before a noun but, as we saw above, they can also come after the verb to be and also after other linking verbs such as stay, look, seem, appear, become, etc.
Study the following:
A tall young man and a petite middle-aged woman were walking along the narrow road.
Tasty, fresh, white French bread is always best served with Stilton cheese and red wine.
The fine sunny weather is set to continue. It will stay fine for the next few days.
New ideas are always interesting and exciting.
For more info, please visit here: http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv98.shtml
Replying to [Vicente]:
Thank you for your input. However it's not my idea, it's from BBC website. I thought it's useful so it's here.