I commute by public transport, and I mostly read books on a Kindle. If I was to use my phone, I'll probably solve sudoku or something. Or maybe read RSSes.
When I commuted (which thankfully isn't very often at all anymore,) I read.
I find that whenever I get myself wrapped up in a project, it's hard for me to take time away from it to do anything else. Thankfully, my body has checks built in (hunger pangs, sleepiness, etc.) to make sure that I'm keeping up with the basics, but I have to set time aside for exercise and stretching or I won't do it.
For me at least, I can't work on the DC metro. It's too crowded, too noisy, but I can read on my Kindle. It's great because it lets me occupy the otherwise wasted time on something that I likely wouldn't get to do without the metro.
If I'm between books, or have a short commute, I'll do crossword puzzles on my phone[1] or play Words with Friends.
If I'm not commuting, I'm lucky to get a half hour a day to read when I go to bed.
For me it is (unrealistic). Every update is fear that something will break. Vim, kmail, even gtk themes. You don't know the day or the hour.
At least that's how it is for me. I know many people who have no problems with updates breaking stuff in Arch; maybe it's the fact that I'm using a full-blown KDE instead of a mere xmonad or such. But I wouldn't recommend Arch to anyone who expects stuff to work.
