I've used as 6" phone for the past year (Lumia 1520) and still used my iPad (Surface Pro 3 since July).
Having a larger phone simply makes it "easier" to do certain things you would always go to your tablet for such as browsing the web, looking at documents, etc. My tablet is still my default for those type of functions, but sometimes it is just not convenient to pull out my tablet and being able to see and share from my larger phone has been a huge bonus (especially when showing pics).
Heading back to Apple (6+ on order) since I couldn't even use my old iPhone 5 after getting used to the larger phone.
Having a larger phone simply makes it "easier" to do certain things you would always go to your tablet for such as browsing the web, looking at documents, etc. My tablet is still my default for those type of functions, but sometimes it is just not convenient to pull out my tablet and being able to see and share from my larger phone has been a huge bonus (especially when showing pics).
Heading back to Apple (6+ on order) since I couldn't even use my old iPhone 5 after getting used to the larger phone.