It provides for cool takedowns, but it has actually gotten Karo into trouble. In the Serra fight, Karo tries a throw that actually gives Serra the better position (In fact, I haven't seen it in awhile but I think that he does that twice). In the Lytle fight, he uses and arm throw (Don't know the name... Seionage or something) that had him drop to his knees and show Lytle his back. Now, it worked, but if Lytle was more comfortable in those situations, he could have dropped his hooks in and tried for a choke.
Against St. Pierre, Karo takes GSP down only to realize: "Damn, GSP is a beast." From that point on, GSP's incredible strength overpowered Karo on the ground. And again as mentioned with Diego, there were a few times that Diego got taken to the ground and Karo gave up a dominant position.
All that said, I think Judo is an excellent alternative from the takedown norms (Your standard shoot to double leg takedowns and leg sweeps). Part of what makes Karo so friggin' exciting is that when he wants to go to the ground, it's going there. But like everything in MMA, Judo isn't the end all be all. You have to learn as much as possible so that you have a full arsenal.