There are potential problems with leased entries in the lookup service. Services and resources may have vanished but the lookup service will say that it is available until its lease expires. Only time will tell how well partial failures are actually handled. Much will be determined by which exceptions are propagated into the client space and which are not. Though Jini is as dynamic as it gets, it requires the use of static, well-known interfaces to access services.
Lookup service is the bottleneck.
If lookup goes down, no service can be accessed. Jini itself will need a fair amount of configuration and administration. All components needed to provide a service need to be up and running. It was designed with Java and only Java in mind. We all know what happens to ideas that are too ambitious.