What do you like best?
They offer discounts all the time for new and returning users, as well as additional incentives to keep you coming back.
What do you dislike?
Their site can be a bit buggy with not letting you upload certain artwork (i.e. the upload will be successful, but it won't allow you to preview it). It's also not the easiest interface to navigate.
Recommendations to others considering the product
One of the best places to get quality stuff. Other places will have higher costs (and yes, much higher quality for most things) and more variety in what you can do, but if you're looking for regular, everyday good for business things, this is the place.
What business problems are you solving with the product? What benefits have you realized?
We order business cards from them all the time. It's simple to create, order, ship, and reorder what we want, whenever we want it. They offer discounts and incentives to regular customers, and they way they promote other product options to you afterward is helpful at times because there are often other things that we didn't realize we'd need until we saw them. It's the small things, like asking if I want business card holders for the cards I ordered, that really have an impact.