Why upgrade from SEL1650 kit lens to Zeiss Lens?
 

For pure comparison I uploaded 2 pics side by side made by A6000 with: Sony Zeiss Sonnar 35/f2.8 prime vs. SEL1650 Kit lens (supposed to be much worse in quality) :

Sony Zeiss Sonnar T : View image: DSC04444

SEL1650 Kit lens : View image: DSC04445

and one more:

Sony Zeiss: View image: DSC04446

SEL1650: View image: DSC04447

The only difference I can really notice is here with text displayed:

Sony Zeiss: View image: DSC04448

SEL1650 : http://postimg.org/image/qgrf3npn3

If you click on the image again, it will enlarge it.

So in my conclusion, for a regular outdoor shooting I could not justify spending $800 for Sony Zeiss, I will never shoot text in a newspaper, other pics show no clear difference to me. Perhaps in lab conditions you can see with human eye, other than that, we are splitting hair and cheaper 1650 is a fine lens for 99% of population IMHO. Or do you see something I don't?

Always hard to compare glass. Best method is to use a tripod and same settings on both lenses to really try to compare.
Shooting out of your hand or different frame are factors you want to exclude.

I've got a buddy who swears by Zeiss lenses on his Sony - but I still prefer my Nikkor for the Nikon.

maybe it's just my old eyes but the SEL looked better to me.