All you really need to know is that they have the most delicious and addictive popcorn ever, at either location. The weekly flavors (one savory and one sweet) keep you coming back often, even if just out of curiosity for some tasty samples. Cheddar popcorn is to die for, and anything with chocolate I feel as though you will actually die if you eat the whole thing yourself. Rotating flavors like spicy bacon cheddar or buffalo wing are delicious and surprisingly vegetarian.
I know the downtown store has a $7 minimum for credit cards, not sure about the Strip. They also make a wonderful gift... good popcorn and a quality tin.
Note: Now they're in Oakland too (woohoo)!