We played for over an hour, and got about halfway though it, I estimate. I typed, and she suggested actions when we were figuring things out, and we had a good time. She caught on very quickly, even to Rover's unusual framework, and learned to skip the room descriptions and other repeated text and read just the new information.
I'd meant to be a bit more scientific, and give her a title to figure it out on her own while I watched, to see how someone would approach IF having no background. However, this was actually enjoyable for both of us, and hopefully we'll finish Rover's, and many other titles in the future together. And, yeah, I'm bragging a bit that I have a wife who'll play IF with me.