We've been running UCC in production since the product has reached GA status. There are still two weird problems I am running into on a regular basis.
Every few days or so, the software seems to stop responding. SNR calls go straight to voicemail without UCC picking the call up and DISA calls just keep ringing and never answer. If I restart the services everything comes back online immediately.
The other problem I am having is with the client. When the client tries to pull a large number of contacts via MAPI the data set gets truncated and returns empty records where the contact should appear.
Both problems were reported to Callcomm, but I still have not heard back from them.