The one area where tablets beat all other devices is reading digital comics. The screen size and resolution are just right. The touch interface is just right.
For just about any activity I can think of, tablets are second-best at best (reading eBooks, watching movies, web browsing), but for digital comics it really is the best way to do it.
Apparently, people do not like walking around all day round with all those best of breed devices (a eBook reader, a full-size cinema, and a desktop PC with three 30" monitors) and/or cannot afford to.
I think smartphones are in the same situation: those sub-optimal tablets beat them for reading eBooks, watching movies, web browsing. One could even argue smartphones aren't even best of class for making phone calls. Yet, almost everybody owns one.
From tablet sales, it looks like people want to sacrifice some portability to get a 'big screen smartphone' in exchange for that bigger screen.
I use a Thinkpad Tablet. I find it absolutely perfect for studying. Switching between course text (pdf) and note taking app (I use a stylus) with the occasional browser search for more info. Oh, and a Scheme Repl for quick tests. And TED talks for time out.
I find that a tablet built for stylus use is a fantastic learning aid. So I guess I'm in the non existant market group that prefers non Apple tablets.
For just about any activity I can think of, tablets are second-best at best (reading eBooks, watching movies, web browsing), but for digital comics it really is the best way to do it.