Only bought a few picture sets for a design from their store, but everything went very smooth, access to content almost instantly.
The only "bad" thing you could say about them is that the web is already full of their content, as a lot of sites, especially "megasites" use it already. But then again it's non-exclusive content, so it would be dumb not to expect that.
So: Nope, nothing negative to say about them
