What really drew me to this series was how truly real, it felt. There's always been a bit of an antiseptic unreality attached to Star Trek and how it really never feels like it could grow out of our world. The Vanguard characters really seem like real people. How they speak, what they do, how they interact... It all seems perfectly realized.
And, I would love to see a movie version, if only to see Ms. Karume cast.
I think OCs feel more "real" because novel OCs aren't subject to "keeping it canon". They don't have to conform to characters built according to the needs and rules of television or movies, which have unspoken (and often spoken) limitations placed upon them by the studios.