I have been standing while working now for three and a half years. I knew that sitting all day every day wasn't good for me, and considering a chiropractor warned me in my mid-teens that I may have back problems when I get older, I decided that I must do something to avoid that prophecy from coming true.
The research I found suggested, for ergonomical reasons, one should position the keyboard and mouse at a level where one's forearms are parallel to the ground. This prevents wrists from bending backwards and creating strain on the tiny muscles in the hands. The research also suggested obtaining adjustable desks, as it is difficult to transition to standing up full time, at least at first. The research on avoiding wrist strain is also backed up by Dr. Aaron Davison at Davison Chiropractic, who has helped advise me on the necessary changes to be successful while standing.
The other critical issue is the positioning of the monitor. Looking down for eight or more hours per day strains the neck, so solutions that position the monitor at eye level help users stay focused on good posture.
I ran into two problems in the getting started process. First, adjustable desks can easily cost hundreds of dollars. Second, many of the solutions involved the monitor sitting on the same surface as the keyboard and mouse, meaning one would look down instead of straight ahead.
Over a period of months, I continued researching and found that Ikea made a desk called the "Ikea Fredrik"; however, they unfortunately discontinued it. Luckily, I found one on Craigslist for less than $100, and I set it up in my apartment. Below is a picture of my setup:
Here is my recommended configuration:
Use boxes or other materials to position the keyboard at the appropriate level, to keep your arms parallel. I purposely setup the desk too low so I'd have room to experiment, and I just never got around to changing the height of the desktop surface once I figured out what worked best for me.
The mouse is slightly higher. It's recommended that it be even so your arms are parallel to the ground; however, I've become used to this configuration and have no problems.
The laptop, and an external monitor, are positioned on the top shelf at eye level. Flat screens and small laptops work best with the Fredrik. It can be wobbly, but I've never felt like there is a danger of anything falling. Still, I wouldn't recommend something large, like a CRT or Thunderbolt monitor.
I stand on old, worn-out shag carpet. This is the one area I need to change. I plan to try a mat similar to what enderland suggests. When barefoot, I do experience discomfort. But when wearing shoes, I find I can stand for much longer periods if I keep my weight on the balls of my feet and my knees slightly bent.
When I first started, I switched between a sit-down desk and the standup desk. The sit-down desk at the time had an old Dell Dimension setup, so the slower computer motivated me to stand more often at the faster, newer computer. Today, the sit-down desk is so cluttered I can no longer sit at it.
I also find I must take at least one brisk 30 minute walk per day in order to keep from getting stiff. If I do this, I can concentrate just fine and accomplish my goals. If I don't, then I find that even after three and a half years, I become incredibly stiff and find standing to be a distraction.
If you're going to stand, be prepared to experiment. Working at a standing desk isn't something you can do full time without a lot of dedication and persistence. Even today, it is something I must constantly work at to maintain. If at first you don't succeed, definitely try again.
is a standing desk easy enough to adapt to so that it's not too distracting from work, and doesn't stay distracting for long?
To answer your question more directly, you will be distracted at first. Mitigate this by having both a standing and sitting option, and if on some days you find you can't stand, don't take that as a sign you can never stand. Just take it one day at a time, and be prepared to fail.