Love my crocs and wear some style of them just about every day!
I got my first pair (the black/red Mickey ones they sold in WDW) and it was the only time my feet & legs didn't hurt at the end of the day!
You have to make sure you get the right fit...they should NOT be tight fitting like regular shoes, a proper fit is loose (they feel like a size too big) as that is how they are made; a tight fit will produce blisters whether or not you wear socks (the shoes are made to be worn without socks, by the way). Most people are familiar with the Cayman style and they are not the prettiest thing in the world. Take a look online at the different styles and if you have an outlet close by go and try some on (I've noticed that many outlet malls now have Croc stores and they have some decent sales). I have sandals, ballerina flats as well as they cayman style, I even have the mammoths with the fleece lining for the winter (very toasty even without socks).
They are made of a bacteriostatic fiber to prevent infections and have built in supports. Be careful though as they can be slippery on wet slick surfaces more so than shoes and sneakers.
Came here to say most of this. Crocs are great, and they are all I wear at Disney, but they must be worn properly (loose). They must also be broken in, so get a pair about a month before a trip and wear them some before you go. If you visit their website, you can find a pair of Crocs to fit just about every style. I have originals, flips, sneakers, and boots, and more than one style of some types. No one has to wear the "ugly" ones to get the benefits of Crocs. One thing that I have found that helps is to take more than one pair, and alternate each day. That can give you different pressure points each day, instead of being on the same ones for the length of your stay.
As for my testimonial, when I first began going to WDW in 2001, I always took a broken in pair of New Balance walking shoes. They worked for a few days, but by about the 4th day, my feet and legs got sore and stayed that way for the remainder of my trips. I learned about Crocs here, and began wearing them to WDW, even though they only had the ONE ugly style back then. I have not had any problems with my feet or legs since. Yes, I still get tired, but not the pain and soreness I used to have.
Another thing that many people don't realize is that you can't "borrow" a pair from someone and judge the comfort based on that. They're not exactly like Birkenstocks, but they do somewhat mold to your foot after breaking them in, so wearing someone else's is not going to feel good on your foot.