Is my account balance publicly visible?
If your business partner knows your address, they can learn the transaction history and balance of that address. Often it is possible to guess or deduce that other addresses also belong to you, but this requires a bit more effort and is less reliable. However, this certainly doesn't translate to your complete wallet's balance and activity to be known.

This is why Bitcoin users are advised to generate a new address for every business interaction they have and why generally Bitcoin software makes it easy to create new addresses.