Recently I upgraded my phone to iPhone 6s. I did not like case on my 5s because it made it very thick and I was not huge fan of that, simple tempered glass screen protector and vinyl skin for back worked just fine for me. But iPhone 6s is very thin phone and it has very weird camera bulge, so putting case on it makes a lot sense.
I started to search for leather case, because leather feels very nice in hand and does not make your 800$ phone look like cheap plastic pile of shit, also it does not look like phone belongs to child. Option 1 was to go with Apple genuine leather case, option 2 was to look at some 3rd party accessory manufacturers. I did not like Apple leather case much, because it goes over buttons on sides and makes them very mushy, also leather case from apple is very thick, there is huge difference having phone with this case and having it with no case at all.
The case is about 1mm thick on back and on sides, it is made from polycarbonate frame to which is glued leather on outside and microfiber cloth on inside. Compared to Apple's leather case this one has leather only on bottom, sides are just polycarbonate, but I personally prefer this combination more, since it allows to make cutouts for buttons rather than have them covered.
Bellroy says that inside of case can be used as small storage compartment for some cash, but I found it useful only for few bucks for an emergency. Case is pretty hard and putting it on and off is not the most pleasant experience, it gets stuck on buttons. I also have metal plate for my magnetic car mount there, so I won't be storing any cash there. But it is good, case sits on phone very well and there is no chance it will ever come off by accident, hard polycarbonate shell also gives very good protection to corners, so the chance of destroying your screen in case of fall is very little.
Overall it is very good product, it comes with 3 year warranty- something you don't see very often and it says a lot about companies overall quality if they offer such long warranty, even Apple themselves only offer 1 year warranty out of the box for their products. It feels very nice in your hand, sides has rubbery soft feeling giving extra grip- something you definitely want for iPhone, because it is slippery as hell. Case costs only 5$ more than Apple's genuine leather case, but it is slimmer and lighter, definitely a good alternative worth to consider. I'm person who have bought a lot of cases in past, but never actually used them longer than a week, but I have a feeling this case will never leave my iPhone, I absolutely love it.
You can buy this case directly from Bellroy: http://bellroy.com/wallets/phone-case?color=black