They're "smart" which means you can form a serial bus of them, query individual motors' encoder positions and motor temperatures and whatnot, adjust the PID parameters yourself, and so on. You can also daisy-chain them together, which might reduce your cable routing problems.
Downside is when they break, you're out $50 or more - and you're going to break at least one. And the manufacturer wants you to operate them at 11.1v which isn't very convenient. And when it comes down to it, it's still got plastic gears, a plastic case, and enough backlash to be noticeable.
Dramatically. They cost (give or take) ten times more and weigh twice as much, for which you get (give or take) four times the stall torque, serial positional control, and a 360 degree range of motion.
Side bar: these servos are a game changer.