Traditional Stereo Vision vs Xtion/Kinect

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What are the pros and cons of traditional stereo vision using two commodity cameras compared to the method used by 3d sensors like the ASUS Xtion and Microsoft Kinect?

I know the Xtion/Kinect have a blind spot within a few feet of the sensor, but the device is entirely self-contained and provides immediately useful data. Whereas traditional stereo vision has a higher computational overhead and usually has to be assembled from various parts, but overall consists of cheaper parts (a couple of $5 webcams and a $35 RPi vs a $160-$270 Xtion/Kinect).

Are there any other benefits or caveats to each method? Which is more accurate?