Do it! I've just managed to do 3km on my daily stand up meeting.

Is it practical for doing like, typing and data entry tasks while you walk?

It's fine. I slow it down when I'm doing a lot of typing, and speed it up when I'm in meetings or doing more admin-style work. Obviously you don't need to be on it all the time too, you could use it as much as you want.

One caveat is that I get very hot doing it, and my colleagues mentioned that they get hot too. I have a tower fan near me that's on all the time. Not much of an issue for the next several months, but it was difficult during summer.