Lumia 1020 here
Upgraded directly from 8.1 cyan. First update was to a semi denim version - 270MB
Second update process took me to 10549 - 750MB
Pros
Lumia camera is back and no way am I hard resetting the phone
Start screen has more space.
Cleaner look
Love the text size slider, pushed the scaling to 175%
All my data is still there, photos, texts, contacts, even whatsapp messages
Better action center
Did I say Lumia camera is back?
Cons
Music app is giving me errors when playing most of my songs. I'll try copying them back from the pc
Can't get to task viewer by long pressing back button. I read another post with the same issue but it's do with scaling issue. I'll change and see