Are you talking about the black part? Then that would be no. I have two of their cases and it's not that hard plastic. I just cleaned a friends 5c who has a Belkin case. I know they don't take it off, but the case got scratched anyway. There was some dust trapped behind it. So far with my Spigen, I haven't seen any scratches on the back. So again the answer would be know. I think you will like the Spigen cases. Check out the Ultra Hybrid too.
In my point of view, it's really better than Belkin Speck. Neo Hybrid is revolutionized bumper case. The dual layer of the case maintains a clean and simple look while providing all-around protection.
What I like the most about this case is the slim profile and metalized buttons enhance the iPhone's overall design and the interchangeable frames can be used for a personal customized look.
Both the outer plastic and the inner TPU are different from the Speck. The speck has a gummy/sticky TPU and the shell is a thin plastic prone to scratches.
The TPU on the Spigen is more like a smooth/matte material, and the plastic is also matte and not as prone to scratches.