You guys really need to find someone who could make some really Quality artworks, if you want to advertise your project using them. These ones are looking more or less like mid-quality fan-art - and so it should be titled, though.
I know that you started from the scratch yourselves and don't want to separate from those who are still learning and gaining skills ( and it's the thing I really anticipate and appreciate about the project ), but they shouldn't be those who make public teaser artworks! ( unless they already gained the Skills, of course - some of them did )
I have seen that you have some newly-hired and already skilled 3d modelers, I don't quite understand why you can't hire equally skilled artworker.
On the topic:
I kind of like the artwork made by Grzegorz Przybys, and I'm really impressed that the last one is made by Krezel (he made incredible progress to me, I would have never assume that he would do such different and really artistically interesting thing. Awesome! )
And the conceptart intoxicate posted a while ago is one of the most interesting 2d picture related to Afterfall I have ever seen. It's a shame that we can't see things like that more frequent.
(and please, fix the typo on it)