Pros: Accurate, dual temp, can measure ambient temp or inserted into meat
I've used this setup with my older WSM (no temperature gauge) to help measure both the ambient temperature inside the smoker as well as inserted into the meat.
One probe is stuck through a shaved down cork, which is jammed into a vent hole on the top of the smoker to measure the ambient temp. The other runs through the smoker door and is stuck into the meat itself.
If I had any gripes, I'd say that it would be nice to have a larger display but all that does is save me a couple steps before I can read the temp.