I bought a lovely Samsung ARM-based Chromebook about a month ago, and I've been using it every chance I get. Here's a few things using it extensively has taught me:
"Disposability" is amazingly freeing. This thing is $250, which isn't cheap enough to not care about it, but cheap enough that loss or permanent damage is more of an annoyance than a serious problem. This combined with knowing that everything I do on it is pretty much instantly synced online means that I just don't stress much about losing or breaking it. That's caused me to bring my Chromebook along in a lot of circumstances where I'd have worried about bringing a valuable object -- and that's meant that I write and "work" more. I like that.
Real keyboards are nice. I used to carry a Bluetooth keyboard with me when I thought I might want to take notes or write on my iPhone or iPad. But they technically don't allow those on planes, and it's annoyingly difficult to use the keyboard+mobile-device combo without a solid surface. And let's face it, the iOS keyboard is just really not great for anything long-form (crazy outliers like Patrick Rhone notwithstanding). Having a "real computer" of sorts that I can comfortably balance on a knee while I type is surprisingly enjoyable.
Most of the time, I need less computer than I think I do. Web apps have gotten amazingly good; but that doesn't help much when you're disconnected. Or if you need to do "serious" work.
If you do any serious computing, a Chromebook doesn't replace a traditional computer. There are some things that there just aren't good web apps for -- and so I found myself using SSH and some form of Remote Desktop or other on a fairly regular basis. In some ways, this was great: working on high-end machines using the Chromebook as a sort of "window" to my real computing resources was the best of both worlds. Until the WiFi got sketchy. Or there was any sort of connectivity problem.
It's amazing how many places have free or cheap WiFi.
But the major thing I've learned from using a Chromebook as much as possible is that tools can spoil you.
I wrote several pieces of analysis software for my current client using my Chromebook. There are not good development environments on the web yet (though Koding is both interesting and promising), so I did this via SSH. Which means I used vim and tmux to write and debug on a remote machine. And you know what? After an intial "this is weird" adjustment period, I got a lot more done.
Sure, the first pass went a little more slowly without the neat IDE features... but I was closer to my code. I knew it better. I had fewer distractions in the full-screen terminal session (which was required thanks to the tiny monitor). I read docs using command-line tools, which meant I was less likely to get side-tracked by some interesting add or notification. I got more done.
I didn't have any games locally installed. Sure, there are plenty of time-wasters on the web, but somehow they're not as appealing as a handy shooter. If I wanted to play anything more than a casual game, I had to switch contexts -- I had to pull out my phone or my Vita. And with that, I was more aware. Hey, I'm not working right now. The games were more relaxing, and less of a distraction.
When network connectivity got poor or disappeared entirely, I didn't have a lot of options. I could write, thanks to Google Docs' offline support. And without anything on the machine to provide easy distraction, I wrote. I wrote more. I wrote more clearly.
The end result of this, though, was not to give up my tools -- and certainly not to give up my beloved MacBook Pro. Rather, it was to much more carefully consider what having a tool (or a toy) will actually do for me. To install only things which will meaningfully improve my ability to do those things I want to do -- to get work done (even if "work" means hobby-work).
And so I rebuilt my MacBook Pro today with these lessons in mind. And whereas I'd previously been frustrated at trying to keep my 128GB SSD free of anything that didn't need to be fast, and make sure I carefully managed my 500GB pack of spinning rust so it wouldn't run out of space... now my entire footprint is less than 20GB.