The UI is absolutely incredible although it wasn't immediately clear to me that I can click on the "How it works" steps to move the slider. You might want to make it more obvious or add another method to move the slider, such as a big arrow to the right with text like "Next Step: Add Basic Info".
How is this 'nice' UI? It is a box with drag to upload written on it. As seen on: every other file hosting site at the moment. The only twist is that to download stuff you have to connect to facebook.
This is literally people charging for the software to do the horrible practice of requiring I advertise your brand in order to get free stuff.
'Like Gating' as they call it is scummy and already widespread enough as it is and they are trying to sell it as a service!
Again, fantastic job on the UI. It looks great.