In terms of the database, ADR could be a great thing. It's integration with Enterprise Manager is probably one of the best parts about the feature. The database manages the retention policy of how long you want to keep these files around based on the scheduler, all things we know how to deal with.
However, you need to be aware that in a client-only configuration (such as a shared client over NFS) there is nothing to manage the logfiles generated by ADR. The logs get place in /var/tmp and could potentially be across every machine in your environment. That could be a nightmare if you're running with several hundred clients or multiple domains. Left unchecked, it could fill up your root disk if that's where you have /var/tmp. I'll leave it to your imagination how I found out about this new feature.
Instead, you might want to turn ADR off by setting
DIAG_ADR_ENABLED=offin your sqlnet.ora file.