I've covered Creative Market before, when it was in the building stages. Back then they were giving away resources for free to entice people to sign up for the site - it worked.
The people behind the site raised $1.3M to help build and get the site up and running - that's a lot of money for a website, but because of their success in other websites, they gained trust from investors.
Creative Market is basically a marketplace for creative resources. You can purchase graphics, templates, themes, fonts and add-ons. Designers can also sell their goods on the market place, but you have to request an invite. The reason for the invite-only limitation is so that the designers who do sell their goods on the site are of very high quality, and so that the market does not get flooded with goods which no one will ever buy or are just complete crap.
Designers get to keep 70% of every sale, they don't have to make their files exclusive to the site, can set their own prices and can upload goods right away and see them sell, there is no product review process. These are things which competitors like Envato don't offer.
On launch day of the site, it already had over 80,000 users - so people are interested in purchasing resources and there are people to sell to.
The UI and UX of the site is spot on. When purchasing a product it's a very simple and fast process if you have money already in your account. Even the animations involved are stunning. Users can also recommend files they've purchased which can boost a designers rep on the site.
There's a nice social element too which lets you comment on items and you'll receive notifications if someone replies or messages you.
If you're after creative resources, Creative Market is easily one of the best places right now.