I was actually tempted to reserve the free upgrade until I saw this video. You're right, we do have an entire year before deciding on getting it free. What worries me is, what if we had to restart our computer and go back to Windows 7/8. Then we won't be able to get 10 for free anymore after a year.
It's been a while since I've used Windows, but I'm becoming a huge fan of how lightweight Ubuntu is. I've became way too spoiled by my Chromebook's speed and simplicity. Ubuntu has the capability to replicate ChromeOS in terms of speed and bootup time. In fact, Ubuntu is better than ChromeOS.
On my next computer, I might just buy another chromebook, or just buy a cheap new laptop and install Ubuntu on it.