Before you read this, I just want to disclose that personally I think that the 1020 is an engineering marvel in many ways.. we are really picking apart very small details that most people won't care about. Also, this is all based on my personal observation and knowledge.. I don't have any professional experience or expertise in the matter.
They have also all new algorithms for color processing and noise reduction..
Well, so far from what we can see those new algorithms are not as good as the old ones. There seems to be more grain/noise in the jpeg compared to the 808..
You could clearly see that the jpeg signature on the 1020 is from the same family from which all other Lumia phones came from. The 808 and the N8 came from a different one.. Personally I prefer the more natural/smooth look of the Dinning era.. I think its better to have natural color reproduction to which you can choose to add saturation, than a saturated one which you have to make more natural.. its a difficult task.
While the 808 took great photos, it is also significantly more chunky....and that's without the OIS rig (which is even more important for video, which a lot of people overlook)...
OIS is very important for video, and I agree 100% with you..overall the 1020 will be much better for video capture, no matter the difference in IQ. It would be negligible since we are talking about 2Mpix images being captured 30 times every second.
However, I can't agree on the more chunky part..
The 1020 is 6 mm taller, 11 mm wider, and more importantly takes a bit more or at least as much volume as the 808.. so when you put it in your hand or your pocket, it will take more room.
The 808 is at: 95.5 cc
The 1020 is at: 96.9 cc
The most impressive part about the 1020's dimension is it's weight.. its 11 grams lighter than the 808.
Source:
Nokia 808 PureView vs. Nokia Lumia 1020 - GSMArena.com
The jury is still out on that one.. if it was indeed that awesome, most high end compacts and DSLR would've moved away from FSI a long time ago. I am still to see a photograph taken with a BSI sensor that tops the N8 or the 808 in terms of raw IQ .. the 1020 might be the first one to beat the N8 by using all sorts of other clever tech.
I recommend reading this paper by Aptina explaining the difference b/w FSI and BSI. I've read it at least 3 times, and for the part its over my head, but I think I got the basic idea, and I can see why the OEMs started pushing BSI sensors over FSI.
BSI allows you to use smaller than 1.4 micron pixels, as the light channels/tubes which guide the light trough the front side (metal) of the FSI sensors can't be that small.. it gets messy. So as the OEMs had to increase the megapixel count, but still keep the same tiny sensors, they opted for BSI sensor and dipped below 1.4 micron pixels.
The case with the 1020 confirms this theory as it uses 1.12 micron pixels as opposed to 1.4 microns on the 808. So.. they kept the megapixel count, but at the same time made the sensor smaller.. its a workaround.
I am not saying that with time BSI won't yield real world benefits, but at this point.. I think its more of a compromise than anything else..
Here is the paper:
http://www.aptina.com/news/FSI-BSI-WhitePaper.pdf
Toss in six lens elements and new algorithms for low-compression JPG processing and the 1020 will go beyond the 808
Making the lens more complex doesn't necessarily make it better..
From what I've seen so far, the optical system on the 1020 is not as good as the 808.. there is visible softness on the edge of the frame, which doesn't exist on most 808s.
Example:
http://www.esato.com/phonephotos/cam/nokia/lumia_1020/2013071119456ov0Ac.jpg
This might also be caused by the auto focus system.. we might have to wait and see. I noticed it on several of the official Nokia samples.
As far as going beyond the 808.. in certain condition, maybe, but overall.. doubtful.
Even side by side 808/1020 shots showed the 1020 being sharper..
They are a bit sharper on default settings, but you can pump up the sharpness on the 808 and you will get a similar result.. but I was never a fan of the over sharpened look, no matter the source.
Here:
http://www.esato.com/phonephotos/cam/nokia/808_pureview/201305172149id083t.jpg
15mpix image from the 808 with pumped up sharpness.. I very much doubt that the 1020 can do better.
Again, just like with the color reproduction, I would rather have a smooth image I can add sharpness to, than an over sharpened one that I have to make smoother..