Going into 3rd year undergrad at UChicago, I've selected all but one of my classes based on having been in at least a few class sessions with the same instructor. (The exception has extremely positive course evals.) I think being in a class with an instructor is the only valuable, reliable, consistently available source of information here - since students vary so much in learning style, learning ability, and background, it's hard to get good info from them. I think students don't shop as much as they could because that requires doing stuff.

The only times I pay attention to course evals is when they are mostly unanimous, or when they give specific indications of qualities that are definitely good or definitely bad. E.g. good: "gives lots of examples quickly, without being repetitive", "the homeworks are enlightening/challenging/not tedious" and bad: "doesn't speak clearly", "gives obscure/tedious homework problems".

By the way, Vipul, I think I have your old Linear Programming book from the Eckhart table. :)