I came to Chrome OS by a circuitous route. Initially I though a browser in a box was a silly, under-powered toy. But then I needed a meeting machine for work.
To start with I decided to use an old Macbook. It was running OSX 10.5 (Leopard) which is a bit out of date so I thought I'd update it to the latest 10.8 (Mountain Lion) goodness. But this turned out to be impossible to do from my desk. Before I could go to 10.8 I'd have to get physical media for 10.6 (Snow Leopard) and patch it up to the point where it would accept an upgrade. This meant shipping a disc or visiting an Apple Store and getting smarmed at. Unacceptable.
So I decided to ditch OSX and install Windows 8. This was a cheap online purchase and a painless install... but Windows 8 is a disaster on a non-touch device. Everything takes an extra few clicks or a half-mile scroll to the right.
Live tiles seem like a good idea until you realize that you're not looking at the start screen often enough for them to be of any value. If Microsoft had introduced a permanent ticker at the bottom of the screen or a secondary tile screen on all Windows 8 certified devices life could have been more interesting.
Removing the start button so you have to go into touch and swipe mode to do anything is a pain. A boot to desktop mode would be great for older devices.
The deal breaker though is the increasingly assertive Windows Update. Twice in meetings it decided to reboot the computer. It used to be you could delay updates for hours but Windows 8 just knows that the latest patch is more important that whatever you happen to be working on and cheerfully pulls the plug.
Admittedly you can figure out how to find the vestigial, non-Windows 8 config for Windows 8 and go to manual mode. And then figure out how to turn off the nagging for not having the recommended Windows Update setting. But but by this point you realize that you've got a operating system that is about updates first and getting work done second. And Windows 8 Windows Update doesn't even update Windows Store apps so you've got a live tile nagging for updates every five seconds as well.
On top on the Windows 8 horror the Macbook was old, heavy and had a puny battery. Also, after installing Windows 8 the only software I needed to install was Chrome and the office VPN client. Once this sunk in I ordered the new Samsung Chromebook.
Setup on the Chromebook is: 1. Login to your Google Account (with support for two-factor authentication), 2. Choose a wallpaper (optional).
I'm not likely to use a Chromebook as my primary machine any time soon. It is however a meeting powerhouse for email, IMs, calendar and note taking. I replaced Skype with imo.im (which I've used on Android for a while). Full Outlook web access took a bit of head scratching - see this post for details. Google Apps and Hangouts work seamlessly as you'd expect. It's light and the battery lasts all day.
The only niggle so far is that Chrome OS doesn't support the flavor of VPN that my company uses. It would be nice to get to the wiki, but it's not a deal breaker (If you have a Cisco VPN that insists on a group name go vote for this bug).
Microsoft and Apple should be really rather worried.
Updated 2013-07-17 13:54:
Two quick updates.
Providing a group name to use with Cisco VPN devices was added in Chrome 28. Unfortunately it still doesn't work for me. I've filed issue 261241 on the chromium bug tracker for this - you can star this issue if you have the same problem.
Skype has managed to block Imo.im so that no longer works for Skype on a Chromebook. I'm using IM+ for now, but it's not nearly as good - it doesn't remember passwords and it keeps silently losing connectivity so it's easy to miss chats.
(Read the full Chromebook adventure: Part 1: Going Chrome, Part 2: Staying Chrome? and Part 3: Leaving Chrome)