I have a saddle brown leather case and a midnight blue leather case for my silver 6s Plus. I love them both and use them daily.
PROS: High quality leather, slim, fits well
CONS: Doesn't offer the highest level of protection due to minimalist design. Probably not a great choice if you are extremely active or if you are generally rough on your phones.
For everyday general use, I think it's fine and looks great. It looks more professional in my opinion. I use the black leather everyday. Some of the cases are just insane though, as if trying to protect it from a comet impact or nuclear disaster.
I tried one out myself, I did however return it. Only reason being realized it was a bad buy since I tend to drop my phone on occasion. But otherwise little time had with it loved it !
I have tried dozens of cases over the last couple years and I always come back to the Apple leather and silicone cases. I think the leather case looks and feels great on the iPhone and I use it daily unless I am working out and I switch to an Apple silicone case. I also think the leather case looks better over time as it "wears"
Don't forget the wear you get on them. The red one comes to mind as it begins to turn a dark color. I don't mind it, I think it adds character but that's not everyone else's cup of tea.