For me, the iPad is mostly a surface for writing on, general admin tasks and basic image editing. The Apple Pencil is the best input device I find. It's not a complete replacement device - it's complementary. Also my 11" iPad Pro is smaller than any laptop and charges off the same charger as my phone so it goes everywhere with me. I'm about to jump on a plane and it has a week's worth of entertainment, music, textbooks, notepad and Lightroom on it and a pencil stuck on the side. This is just perfect for me. But try and replace a macOS machine with it and you might as well chop your fingers off.
The keyboard case is mostly ok but I just never use it. I should probably bounce it on eBay at some point but I keep it around "just in case".
Edit: most of the people I know who use iPads got them mostly for the Apple Pencil support.