I have the RX-100 M3, too. My main complaints revolve around the incredible complexity of the camera and its tiny size. Yes, it fits in many pockets, but there are drawbacks. My other camera is a D800, my sixth DSLR.
Tiny buttons are easy to accidentally push when you don't want to and difficult to push when you do. The four-way controller is very prone to inadvertent and imprecise use. I find that I need to shoot it regularly in order to keep my skills up to date. The camera will sometimes start doing things I swear I didn't ask it to and an RFTM session is required to restore order.
The camera makes excellent still pictures, the lens is excellent and the look-through viewfinder is exceptional. Recently, I was able to shoot on a sunny day in a snow-covered landscape while wearing polarizing sunglasses. Quite a feat for an LCD viewfinder.
Most disappointing for me is the camera's hand-held video performance. The video imagery itself is fine, but it's often too shaky. I've used many cameras with Sony's Steadyshot function in the past and always been amazed at how well it works, but it seems that the hand-induced shaking that results from the RX100's tiny size and low mass exceeds Steadyshot's capabilities. You can invoke additional levels of IS, but at the expense of reduced angle of view.