The biggest thing that has kept me from doing more of this since getting married was the ability to store the things that I purchase! Our freezer at the condo was rather tiny. We were doing good to fit all of our monthly groceries in at once. But our new freezer has remedied that problem. We have one bin for our meats, another for the vegetables, a top rack for ice cream and fruits, and another for assorted small products like butter, cheese, bread, nuts, and more. And if it doesn't fit in its designated category, we must eat it immediately.
Most "big box" stores are now much better at packaging things in ways that are most convenient for the average family. Instead of buying the lunchroom-sized cans of green beans and corn, you can buy a case with 12 "regular" sized cans in it. Instead of the bag of chips you could crawl inside (and will probably go stale before you eat them all), you may get a box with two individually sealed bags.
One thing I have learned from my bulk buying is the art of re-packaging. I know it's probably not the most eco-friendly way of doing things to take a bunch of chicken breasts out of a single package and put them into individual plastic bags, but it makes life SO much easier when I want to cook and helps me reduce waste, so no chickens had to die in vain. Vacuum sealers are excellent for these endeavors. If you don't have one yet, at least look into a Handi-Vac or something similar. They aren't exactly professional quality, but they definitely do better than trying to squeeze the baggie! And with dry goods, you can often re-use the bags!
For the most part, bulk buying is great. But it does require a certain amount of attention and detective work. You have to know what you normally pay for the stuff you buy! For example, I know I normally pay somewhere between 89 and 99 cents for a box of onion soup mix. So a pack of 3 boxes for $3.64 is available, I know it's not such a great deal!
Some things it's not worth buying in bulk unless you're feeding a group. Produce is one of these. Unless of course you plan to do some canning. I really should look into that...
Stuff that doesn't spoil like household products, paper goods, pantry staples, and the like are perfect for buying in large quantities. Just make sure you know that you like whatever it is you're buying. Otherwise the process of getting it all out of your house without going nuts can prove somewhat daunting.
If you have the space and the time, it is a practice I highly recommend. If you don't have the space on your own, consider splitting a membership with a friend. It's worth it!