Pros
Costco is a good employer, especially if you are a college student or never went to college. Unlike competing retail or grocery stores, Costco pays employees above the market rate while also guaranteeing pay raises--based on hours accumulated at work--up to a more than reasonable level. While I was working at Costco, I started off at $12 per hour while Sam's was starting employees off at $9 per hour and Wal-Mart at around $8 per hour. Other local grocery stores in the area started employees off in the $8-9 per hour range as well. If you never got a single promotion in any form whatsoever, you could still work your way up to $20 and some change per hour as your regular (non-overtime) pay rate, which is roughly the same hourly rate as an entry-level supervisor. To make things better, Costco also provides an excellent benefits package as well as premium pay on Sundays. The premium where I worked was 1.5x your standard pay rate--just for the simple fact that you are clocked in on Sunday. My $12 became $18 per hour and as a college student at the time, and supervisors made $30 per hour instead of $20. Again, not for overtime. Just for working on Sunday. What employer treats their employees this well? You also have the ability to work your way up the corporate ladder with or without a degree. The department managers at the location I worked at earned salaries between $60-80k per year, and many of them did not have degrees. I'm sure you'd hit a ceiling after a while if you never got a degree, but even if that ceiling is an $80k salary + full benefits, that's much better than just about any other company would offer an individual with a high school diploma. (For the record, the store manager at my location started off in the front-end department sacking groceries for customers, and worked his way up to being in charge of an entire Costco store. Not sure if he has a degree or not, and it honestly wouldn't surprise me either way. I'm sure he is pulling in a six-figure salary, plus performance bonus, plus full benefits package.) If you did earn a college degree on the other hand, Costco makes a pro-active effort to place you in an area where your education and skill set is utilized. Marketing degree? Marketing department. Accounting degree? Accounting department. Management degree? You'll probably get fast-tracked to a management position in the store, or get moved to the corporate location. And if you do go corporate, then even more opportunities become available. If you're interested in learning more about Costco, search for "Costco Craze" on YouTube and watch the video. It's a 45-minute documentary that goes into much greater depth than what I've shared here. To conclude, my personal opinion is that Costco is an amazing place to work if you don't have a college degree. If you do have a degree, it's still a good place to work (especially if your degree isn't particularly marketable, such as a liberals arts or social sciences degree). If you have a degree in a subject that's more in demand (think business subjects + STEM), you can probably find a much better job than anything Costco has to offer.
Cons
Jobs are extremely boring and tedious. Not intellectually stimulating or emotionally rewarding in any way. (Exceptions do exist, of course. But chances are you won't be the corporate wine buyer, chief marketing officer, or CEO.) When you're slammed with stuff to do, it's all mindless work. You're running around sacking groceries, organizing carts, making hot dogs, folding clothes, doing data entry, sweeping the floor, etc. And when it's slow, you are pretty much watching the clock and counting down the hours/minutes/seconds until your shift is up. Quite frankly, your academic status (i.e., do you have a college degree and if so, is it an economically valuable degree?) will determine how the pros and cons of this job balance out in your particular situation. If this is the best job you can get from a financial standpoint, then yes it is worth it. Be a good employee and work your way up as high as you can. If you can tolerate the dullness of the job, Costco does provide the opportunity for you to build a financially stable future. If you have better financial opportunities available to you, then I'd recommend seeing if you can get a more satisfying position at Costco corporate. (At minimum, it'll be like any other corporate job you'll apply for anyway.) And if that doesn't work out, then obviously you can find something better.