I've looked a bit through the documentation and noticed how exception blocks are translated to the Objective-C version (@try / @catch ...). Of course most often Objective-C coders would use NSErrors through indirection pointers in situations where Java coders would use exceptions, the use of @try / @catch is often discouraged. This is just 1 example of a possible issue, I also don't like how the namespacing is being handled (camel case name of the Java namespace). In Objective-C we're used to a 2 or 3 letter prefix. Because of issues such as these I wouldn't be very inclined to use it in my own projects.
When it comes to exceptions, its not even a matter of semantics and needing to be very clever. There are cases where exceptions in Java just don't carry over to Objective-C.
A really good example of this is NullPointerException. Objective-C lets you message null (although, its called nil in this context) without any problem.
