Our previous TV was a 62" Mitsubishi DLP Rear Projection and after another "glitch" in it's systerm we decided to upgrade. This VIZIO took us by surprise when we first saw the quality of the picture. Not that the other was bad on our DLP, but the difference in the clarity of this TV took us by surprise.
1. I bet the inner lens needed cleaning which would account of probably 1/2 the difference,
2. The technology of DLP RP vs LCD makes the other 1/2. LCD is crisper with an enhanced edge appearance which to the untrained eye might look better. Also, as long as the source is actually HD, LCD looks very crisp, DLP will have a slight tendency to soften the image, which makes non HD look better, similar to Plasmas. Text will also look much sharper which is why LCD's make great PC displays and Plasmas do not.
I also bet they never tweaked the default "torch mode" settings either.