This really depends on your shopping/eating habits. I'd go in to the customer service desk and let them know you'd like to try it out. They'll usually happily give you a "day pass" for lack of a better word, so you can go do some shopping and see if it's worth it to you.
I have my membership through DH's work, so we don't actually pay for it, so for us it's a no-brainer. I go a few times a year, and stock up on things that are cheaper there, since I can get some things in larger quantity than anywhere else (like a 5# bag of organic quinoa, or a 3# brick of Philly cream cheese), and some things cheaper than anywhere else (like bricks of Tillamook cheese, or clamshells of organic blueberries). But, before DH's work gave us memberships I didn't have one, because it is only a few (smallish) shopping trips a year, and it is out of the way (closest one is about 35 minutes away with traffic). However, I have a good friend who I take with me when I go, and she leaves with an overflowing cart every time - so it's so dependent on your life.