[One (M8) General] hamdir:
This is a physical problem and so until some new magic appears there are physical barriers to what you can do with a tiny mobile sensor (it's a miracle what was achieved already)

Other phones going higher in MP are forced to reduce the pixel size further and further in order to fit them in the limited space, one you approach 1.0um pixel size the pixels lose their precision and start to bleed into each other, this is why see you them rely on extreme noise cancelation in order to hide all that chromatic noise, the results is a water color painting look when viewed at 1:1 (any Z1, SGS4 or G2 owner knows all about that) so how do they pass? well since they are 13MP you have a lot more room to resize and when downsampled they get cleaned a little and become accetable when you view them in smaller scale, this is in daylight, now in low light it gets even harder as the pixel imprecision barely catches any detail in low light so they compensate by slowing the shutter and allowing more exposure time (which is why these phones suffer from motion blur or out of focus issues in non favorable low light)

HTC went the other way, by using a pixel of the least acceptable quality they can't add more as they need more z depth for the sensor and they dont want a camera hump in their designs, so they limit to 4MP good quality pixels, pixels which allow it to be usable in low light and even darkness without slowing down the shutter, even better in low light night mode will slow the shutter just a bit and get you even more light, using HDR in low light simply does miracle, so even in normal mode super fast shutter can get usable photo and a lot more room left for slowers modes to get even better results, compared to other tiny pixel phones who are forced to slow down the shutter just to get any usable result in non favorable light

Like I said the fact that the HTC One photos are viewable and acceptable at 1:1 is a testament against all other phones with smudgy 1:1 results, basically HTC is doing the right thing here

Only the Z2 is doing something else and combating the imprecise tiny pixels without smudging, the results are still noisy at 1:1 and still need downsizing to clean it but it's much better than a water painting look, details are still intact however I don't know about its speed and usability yet

As for the depth path, well I would have preferred they use it to do better exposure metering, I would be suprised if they don't already, outside few courageous devs I find it hard to imagine that we will see a lot of dedicated apps for one device in the android world with this camera setup, HTC however will sure be improving things as they promised to improve the ufocus algorithm and we all know how much they have improved the M7 in software, they will add few more post effects for sure (example you can use zdepth to darken or fog the background as you go further away, or add lens flares occluded by the objects in front like behind trees) better motion detection is also an ability of such camera with depth info so it can be used for augmented reality apps, where it can properly place the virtual objects in their space but like I said I doubt we will see a lot of usage of this API until other phones join the fun

Finally no I am still waiting anxiously the #HTCOneM8 official release in my country all my comments are coming from my experience with the M7 and studying the results being posted on this thread