Thanks for sharing, but I will probably pass it by. As a general precaution,  I stay away from MANY art/vector/photo sites, most particularly those that aren't clear about who are the owners of the site, and where they're based. I prefer sites that, among other qualifications, have a posted way to contact them, and a vehicle for reporting copyright violations.  
 
This site may indeed be fully legit, but one always has to be extremely careful when providing any site with your email address and/or payment information, and accepting their downloads. (Btw, in additional to free photos, this particular site does sell photos and claims they will go to a charity, which is, of course, hard to verify.)
 
In this case, I'd certainly wait many months to see if it stands the test of time without complaints.  
 
Overall, I surmise some percentage of art/vector/photo sites serve no purpose but to acquire email addresses for selling to spammers. The trick is figuring out who's a legit and moral art-services provider and who's not. Caveat Emptor!

I saved a photo from their Facebook page, uploaded it to Google Images and that led me to Picalls.com. Picalls has a similar website with many of the same photos as NegativeSpace, but their contact info is also nonexistent.  

I agree Doreen, but I don't think they should be advertising any commercial use on the page.