I don't like them based on my admittedly limited experience. Your choices are Apple, which has a horrible, locked-down software ecosystem, and a stupid setting layout, or an endless pick of Android ones with shoddy build-quality. There's also the Surface, but that's just a low-spec Windows laptop with a gimmicky form factor.

The whole concept is questionable, and the only real advantage it has over laptops is when you're using it without a hard surface, like on your bed. It encourages simplistic user interfaces with overly large buttons, which is annoying since that also affects the desktop.

If it has a good screen might do instead of a ebook otherwise I'd rather have my Linux(tm) laptop instead.