Honestly, that end of things is kind of out of my element; I'm mostly involved in the message plumbing side of things.
Our actual HIE integration has been contracted out to Relay Health/McKesson. They're promising the world, but we're not far enough along for me to say whether they'll actually deliver at this point.
I'm pessimistic that we'll be able to achieve true level 3 interoperability, even though the basic ontologies (e.g., SNOMED, LOINC, etc) are in place. I'd love to hear that you're having a good experience, though.