Kestrel does it as well. The new Specialized Tarmac looks from pictures to have some internal routing also, though I haven't seen one up close.
I don't think the pros and cons are a big mystery -- what's good is that it's unique, slick, and clean; it's a indication of strong craftsmenship. It's also nice to worry less about under-top-tube cable rub when carrying the bike or mounting it on a rack. What's not so good is just as obvious -- it's an additional complication when it comes to assembly and servicing. If things go wrong with your cable system, the routing becomes that much greater a hurdle.