Interoperation with Java from Clojure is generally fairly painless. The largest exception that I can think of is if you are trying to integrate with a library/framework that is heavily object-oriented and requires class inheritance. Clojure is very opinionated on the functional programming aspect, and although it is generally possible to extend classes, it can be relatively painful.

However, if you are only using objects, calling methods, or even implementing interfaces, interoperation for Clojure is quite nice.