I own that case (since 3 days after getting my phone) It hasn't "yellowed" but the back has scratched as it is kind of "soft". I have the blue trimmed one.
I am of the who cares mindset about that, because what I DO have is good protection for my phone which I've accidently dropped twice on concrete since getting the case and no issues. While it is easy to SAY, "Don't drop your phone, dummy." accidents happen.
So, yeah, I recommend this one. it adds MINIMAL bulk to the phone but shows off the brown leather.