I've had one but sold it.
Started with a standard desk and a Staples office chair but had back problems. Switched to standing but had foot problems. Then I switched to the treadmill desk.
I eventually resold it for numerous reasons. On the one hand it is fairly comfortable to walk while working. On the other hand it's impractical to do so barefoot which is how I like to work at home. They're also noisy, cumbersome to move, and they do break down eventually at a big cost to repair or replace. Also keep in mind that you're prone to shake/wobble your work surface slightly which gets annoying after a while. You'll need a sturdy desk with drawers/shelves of all your supplies nearby and not a crappy melamine table like the one in your link. They also do not offer a place to sit when you get tired and you will eventually get tired of all that standing/walking.
You can mitigate all of these issues in one way or another, if you're willing.
After that I switched back to a conventional desk with a Humanscale Freedom chair. Still had problems so I now have a fixed-height, custom built (by me) standing desk. I use Salli saddle for when I feel like sitting. I am thinking of switching out the gas cylinder for the tall version and getting the foot ring but am not 100% sure I want that bulk.