[Xperia Z3 General] juanmaasecas:
1. Burst mode was the best choice in VERY good light scenes since there was no noise reduction at all (you got the best detail, but also a lot of noise in darker areas and "black random spots" in all over the picture). But it was before 4.3 update in Xperia Z0. After that, burst mode could be used in superior auto mode when holding the shutter button only, there was no a single mode for that anymore, although I think it worked the same way when you selected "fast mode" instead of "normal mode" speed. But take into account it was on Xperia Z0, I'm not sure how it works in new phones... And as I say, it was the best choice just in very good light conditions because burst mode is actually a "high shutter priority mode" which rises up the ISO too high when the scene is a little bit darker than perfect.

2. Camera360, enabling the max quality and the HD improvement allowed me to get the sharpest pictures with the phone when I couldn't use burst mode (because of the non-perfect lightning), but in expense of having more jpg compression artifacts. You can try how it performs in the new Z3, it's a free app :D

3. A better camera takes 3 pictures instead of 2 in the stock app, but it's slower in doing it so it's easier to get worse final picture quality when the app merges them. The pictures are very impressive (sometimes exagerated) while the stock app is more natural when processing. If you are into details, you could use Camera FV-5 and shoot some bracketed pictures and then merge them manually in Photoshop PC. This app allows you to take up to 7 bracketed pictures, so the dynamic range could be really impressive.

5. Night scene uses very slow shutter speed (the minimum was 1/2s in XZ0) and very low ISO level (only up to 100 in XZ0). Using this, you can get very good detailed low light pictures, but you need to hold the phone somewhere (or use a tripod), and since the ISO doesn't go too high, sometimes you'll miss a brigther picture... You can solve it while using ProCapture app. This app tricks the Sony software and allows you to rise the exposure values when using scenes, so if you turn it in +2 eV in Night Scene mode, the ISO level rises up to 400 instead of 100 (so you get a lot brighter pictures keeping the slow 1/2s speed). It was the best for me in taking low light pictures, but I can't be sure it works the same way in the new Xperias... If you can't hold the phone but you still have steady hands, you can use "night portrait" scene mode. In this mode, slowest shutter speed is 1/4s, so you can achieve very good results shooting handheld. High ISO mode is a high ISO priority mode, so the phone uses a high ISO value to keep using fast shutter speed (to avoid shaking and capture still moving objects). But in consequence, you have low quality pictures with a lot of noise... I wish I could try an iPhone 6+ by the way, I'm highly surprised with my new iPhone 5s :D

I wish every Android phone got RAW support and manual control APIs when Lollipop arrives, but probably only nexus and a few other brands implement these new features (I'm trying not to be very optimistic, I know...), so don't expect miracles in the Sony imaging processing area, it's like if Sony doesn't want their phones to compete with their point and shoot department in image quality...

Pd: finally, the worst thing of all in my opinion is not sensor/algorithms, etc but LENS. Sony, HTC or even Nokia persists in using very wide angle lens (28mm in Z0/Z1/Z2, 25mm in Z3!!). I hate this: lack of sharpness in corners (and not so corners...), deformed lines, horrible faces, a lot of aberrations... I prefer Apple and Samsung approach: 35/31mm (respectively): less distorsions, way more natural portraits, better sharpness overall the picture frame... But using wider lens they can develop an slimmer camera module, and slim phones is all that seems to matter nowadays... Do you imagine how thicker would it be a Lumia 1020 with a 35mm lens (instead of 25/27mm)? The camera bump would be a lot bigger...