My work over the past 6 months has varied between programming (small component of my work), extensive spreadsheet monkeying, writing quick reference training documentation, end user training, project management, and an embarrassing amount of emailing. I haven't noticed a drop in typing speed, and for any work that needs more dexterity, I just slow down the treadmill. If you get the treadmill moving slowly enough, there shouldn't be much degradation of your working capabilities at all. Also, somewhere else in these comments, someone recommended a trackball instead of a mouse, which actually makes a ton of sense to me after my experience.
As for eyesight/reading, I'm a tough person to speak on that as my eyesight is pretty good. I have not noticed an issue there; my eyes don't seem to have an issue locking onto words at a strolling pace. I think I might actually have to hit a full jog before noticing any difference on that front.
As I mentioned in my original post, mousing at faster walking paces was the most challenging thing for me.
Also, I would think that working at a standing desk for a few days would actually be a good trial run. It will allow you to get used to spending more time in an upright posture, which is a significant adjustment. I think it's helpful to start out only doing that for an hour or two a day and then increasing it as you like it. You can get a taste of it by putting a box on a counter top with a laptop on it and working for a couple of hours. If that feels like an improvement, then keep doing more. If it drives you nuts, then you've saved yourself some time and money. Lastly, I also tighten up some as I stand/walk, which makes me stretch every now and then. I didn't do this at a seated desk but probably should have.
I put together a treadmill desk about six months ago. Typing/mousing and walking is definitely a consideration. I had to reduce my mouse sensitivity slightly, and I also have to keep my walking speed at or below 2 mph in order to have any chance of typing accurately. I find I'm quite accurate at 1 mph. I reserve 2 mph for times when I'm mostly reading.
I also was unpleasantly surprised by the prices of the commercial offerings for these desks. I'm currently using a DIY cardboard desk and have a carpenter building a custom-made wooden desk, which will still be cheaper than the commercial offerings.
Regardless, I got into this because of 1. Ergonomics - sitting kills my back and 2. Health - this allows me to put in a decent amount of exercise with little to no joint impact while I work.
Plus, I'm slightly less stressed if I'm walking as I work.
Downsides: Until I get into the "zone" as I work, walking and managing a computer is annoying. Decent treadmills take up a ton of room. It's noisy enough that I have to stop it every time I get a phone call.
All in all, I'm glad I did it. And it provided me with a great excuse to wall mount a 60" HDTV as my computer monitor.
I’ve been using Skype over 3G ever since it came out (first with VoIPover3G, now with 3G Unrestrictor) and I have to say that quality sucks. I get dropped calls, sound dropping in and out, weird noises during the call, etc."
We have the largest and fastest 3G network in the world here in Australia (44mbps downlink in the cities, 21mbps everywhere else – 99% of the population have 3G), and being a fairly small population – congestion isn’t an issue. VOIP over 3G works, but it totally sux. Like really, unless you can’t afford to make a phone call (unlikely if you have an iPhone) then it’s not worth the mucking about.
Cellular data connections are very bursty with high amounts of latency. Fine for browsing the web, or streaming media where the player has a buffer, but pretty awful for having a real-time duplex conversation. Which is why I really am ok with just using Skype over wifi.
A few people post quotes to the effect "quality is so-so but it's good enough for me," but most responses seem pretty negative towards the call quality.
Any given program will expand to fill available memory.