A few years ago I played with some of the initial 2-in-1 computers and they felt a lot more like the worst of both worlds than the best at the time. The 2-in-1s I saw on my recent visit were much improved. The devices were lighter, the screens were brighter, and some of them had plenty of power to get most computing done.
This is a sneak peek at an article I'll be writing soon, but my wife upgraded her laptop this month. She went from a 2015 MacBook to a 13” Dell XPS, a 2-in-1 laptop. The screen flips around and you can technically use it as a tablet as well, but I wouldn't recommend it.
As David mentions, these devices used to be the worst of both worlds, and that is no longer the case. The XPS is a fantastic laptop, and when used in that form factor it's really excellent. But when you spin the screen around to throw it in tablet mode, it all falls apart for me. Not only is Windows a major pain to use in tablet mode, but imagine having a tablet that weighed 3 pounds and was 0.5 inches thick (aka 2x as heavy and 2x as thick as the iPad Pro). And while the keyboard on the back on the device is annoying on the iPad Pro as well, you can take the keyboard off the iPad, but it's locked in on the XPS.
In my opinion, the stuff Microsoft is doing with the Surface line is the most compelling 2-in-1 work on the market today. I look at products like the Surface Book 2 and think "yes, that's it!" Take any other issues you have with it aside and from a purely form factor perspective, it's built to be great in laptop mode and tablet mode, and it does so by making the keyboard detachable. Us Apple-centric folks may not like Microsoft's OS as much, but if a MacBook Pro came in this configuration we would be all over it.