What is the differnce in meaning between the following sentences?
It is nice working with John.
It is nice to be working with John.
It is nice working with John. is a general statement.
It is nice to be working with John. is more specific. You are actually working with him right now. Right now can mean at this moment in your life or at this specific moment in time.
The latter form, "nice to be doing", implies that the person in question doesn't usually do anything much. For example, a retired person who does voluntary work might say it.
It is nice working with john.
It is nice to be working with you. I do not find any difference in meaning between the two sentences.
(It is ) nice to work with john seems possible
I have referred to many on line dictionaries to know the usage.
Here is a link which shows the usage.