No offense, but I think you're the person with an RT, which is completely different than what the surface 3/pro 3 are. It would be analogous to trying to give a review of the iPad Air 2 based on only owning an iPad 1.
Anyway -
I sold my 15" MacBook Pro and 11" air because of the Surface Pro 3.
It fit my needs and actually did much more for me than those MacBooks AND my iPad Air 2.
StaffPad is absolutely amazing, and after years of trying to make writing music on the iPad work - StaffPad blows it out of the water completely. Same for OneNote - I've used GoodNotes for years and tried to go paperless - until apple embraces a native active stylus - there's just no competition.
Same for PDF - if you're someone who needs to write on them and do markups - iAnnotate was my go to app on the Air 2.
Not anymore! Drawboard PDF is leaps and bounds better.
I don't really play games - but hello! Sudoku and crossword puzzles on the SP3 allows you to actually write on the game board.
One of my favorite uses for it is taking notes using split screen. I really kind of think splitscreen on the Air 2 will be a mistake (more so a gimmick).
The areas that make having split screen useful are too limited on the iPad, and the screen is way too small.
No, it's not irrelevant at all. You know why? Because it's the apps I'm referring to. The modern apps selection is pitiful. That is why the Surface fails as a tablet. Desktop apps are not a replacement for tablet apps, so therefore, the Surface is a bad tablet.