What is so great about Krishna?
To know Krishna, first we should learn about gods like Shiva, Brahma and other Gods. That is where, you'll find the difference between all other gods and Krishna alone. Krishna holds the multiple personality. He's a multidimensional god. He's like a mirror and reflects just what you want from him, which is unlike other gods. For example, Lord Rama can not be framed into a situation where he plays with girls and steals his clothes. He can only be framed in following the right path. But where as Krishna can be framed in both the sitatuation.
We can see him dancing and playing with girls (gopis) and teasing them. Also, we can see him as a great warrior when he fights with Jarasangh and other kings and demons. Krishna is a beyond personality, that those who claims they've known him, remain in more delusion.
Krishna is very much available for a child but very hard even to think about for a Gyani (intellectual).
So what is so great about Krishna? Krishna himself is a great phenomenon. Read more about him, and you will realise it one day.