People sometimes think I am obsessed with keyboards because I have strong views about them. So, let me put my views up front.
I like good keyboards.
I have always liked Thinkpad/Lenovo keyboards. And I typically use an external keyboard even with a laptop when in my office - the reason: I am a big fan of ergonomic keyboards such as the Microsoft ergonomic keyboard. It's the one with the hump in the middle so your hands are turned slightly up in the center, and even more importantly, it has a raised wrist rest.
Along with my ergonomic keyboards, I like my vertical mouse. It's a traditional mouse rotated 90 degrees so your wrist is not twisted. I learned about it from a programmers whose RSI was so bad, he had to give up programming.
More recently, I have purchased the rather elegant Logitech keyboard for Acer Android tablet. It's not a great keyboard in the sense that the Microsoft ergonomic keyboard is. But it is dramatically better than typing on the glass of a tablet. It's softer on the fingertips. It's faster. And even more importantly, it uses its case as a stand, so suddently you have low cost laptop for taking notes in meetings. Combine the keyboard, the case as stand with a $14 stylus and you have quite a useful little device. In many ways more useful than a tablet.
And because the distance between your torso and the tablet is short, there is little sense of having to over reach with the stylus. The whole combination works well. I even use the stylus on the keyboard and have gotten accustomed to using it my phone when the stylus is easily available.
You can, of course, pick up the tablet and use it with your fingers or the stylus, but those who I have influenced to add these apparently needless accessories (there is also a version for iPad), have had, as I have had, the sudden and unexpected realization of how much more useful they become.
It perhaps also explains the popularity of the ASUS Transformer which combines the form factor of a notebook with the detachable tablet.