The vast majority of my work is done on laptops/computers. However there are times that I find paper and pen best, mostly for:-
Planning - the ability to connect words and phrases spatially or graphically helps a lot compared to the forced linear arrangement when typed
Design - sketching out how a user interface should look (or plans for where an object should be located in an environment) is a hassle with a mouse.
However retention of the results of my scribblings is tough mainly because of the additional steps involved (mostly I'd take photos of the results, the collating and sorting of those interleaved with my other photos is a pain), and that actually discourages me from even picking up the pen and paper in the first place.
What's the utility of a graphic tablet (in combination with my existing laptop) for replacing pen and paper? I'm avoiding options like the Surface/Galaxy Note which would require a new/different device, because of lock-in and limitations in selection (I'm quite picky with the sort of laptops I use/buy).