I'm still deciding on what type of case (if any) to use with my S5.
I've never been a big fan of this type of rugged case because of the bulk they add to the phone. This one is probably one of the smaller ones, which is a plus. The TPU part of the back fits just flush with the camera protrusion in that spot and then adds a slight ridge around it. The frame in the front seems slightly deeper than it needs to be, but it doesn't interfere with using the phone.
The overall look is really good - seems to be a common design. The interchangeable backs I think are great. They look and to some extent feel like aluminum although they are plastic. Everything fits very tightly. Nothing is going to come apart accidentally here.
One concern I had was the cutout for accessing the already-difficult USB port cover. It is indeed quite deep but there is just enough room for getting a fingernail under the left edge of the door. It doesn't really interfere with the opened flap or the cable.
The buttons are easily accessed through the case -- too easily, I found. I am constantly accidentally unlocking my screen in my pocket - not good. I would prefer a little more texture to them so that you can tell by feel if your finger is on one, but that doesn't help the pocket issue.
The screen protector is for me a major killer. It absolutely kills the look and feel of the screen, but even worse, the opening for the fingerprint sensor seems to be a lint magnet. I have a ton of lint and dust between the phone and the protector after about a week. If I absolutely loved this case in all other ways, I'd cut the protector right out. Really don't need or want it.
Generally speaking though, in all other ways it's a pretty nice case, and a good option among this type.