I have a chromebook at home and it has replaced my "serious" laptop almost entirely. Everything I do at home other than games can be done on the chromebook and it's so light and fast to boot I don't bother even opening a browser on my big laptop. Everything done in the browser gets done on my chromebook and only when I want to play games / use windows-only software do I boot up my other laptop.

I can't do anything more than 'consume content' with a tablet; not without adding an external keyboard, at which point you're basically creating your own chromebook type thing anyway. Recently I got the Dell XPS 13 with Ubuntu, and that actually reduces my tablet usage a lot: when reading with a tablet, on, say, a site such as this one, I invariably end up wanting to reply but loathing/dreading the thought of typing stuff in on the screen which is S....L....O...........W. With the new computer, which is more comfortable and portable than what I had before, I can just use a real computer rather than the tablet.

What sort of casual work would be better on a tablet than on the chromebook? Answering emails would be better with a dedicated keyboard, as would navigating in a web browser.

For casual use otherwise (movies, books, angrybirds/candy crush style games), then a tablet is probably a better tool.

What about casual programming? Still kind of a sore spot for tablets - if I'm wrong, please tell me why! If I could just do simple emacs/bash stuff with perl/python/javascript/html and maybe even C/C++ I'd be a lot happier buying a tablet. Not really sure if you can do this with a chromebook either, though. Can it run a modern linux distro?

Cheap linux notebook => chromebook

Price aside, I don't see this replacing my 11" MB Air any time soon.