From this sentence, we can infer that Beethoven likes children. That he took time to play with them and they all had a great time, that is why the children ask him to stay a little longer and keep playing with them.
We can infer that he is creative and fun to play with and that he is has a kind and nice, friendly personality. Also, that he is a patient person who enjoys entertaining other and make them have a good time. He is probably a generous person.