Agreed. I've had TS12 for a couple weeks now and haven't even run on any of the other routes - Mojave IS the reason for the game. (Not to discount the other routes...I hear they're nice, but if you like big time American freight railroading, this is the place to be!)
Add me to the list of people who think the route is worth the price of TS12. As a long-time fan of 3DTrains' version of this route for MSTS, (and someone who has lived in Mojave, Tehachapi, and Bakersfield), I just had to buy this the minute I saw it. I'm glad I did. It's very good, as is the included rolling stock.