From Longman Dictionary of Contemporary Englishsomebody is (great/good) funsomebody is (great/good) funBritish English used to say that someone is enjoyable to be with because they are happy and amusing You’ll like her, darling, she’s great fun. → fun
Examples from the Corpus
somebody is (great/good) fun• Much of the film is fun, but a lot is confusing.• This is just a whim but it is great fun.• But it is fun for me to look up from my Sunday paper and watch them try to cope.• It is fun to have competitions to see who can sleep their yo-yo longer.• Chasing and racing is fun for a time but you end up yearning for something different.• Some of this is great fun, but it pulls the production two ways, blunting its focus.• This is fun, unfussy, honest fare that calls for a glass of cold beer.• In beautifully landscaped settings, this unique zoo is great fun for all the family. 