I have one of those! I sometimes use it on my bed to pedal my arms out of boredom, even if I've already done my cardio. It's something. I let my son, who is too short for the recumbant bike, even if he IS pretty giant as far as most 6 year olds go(4'3.5" and 75lbs). It's good for when it is too cold or wet for him to go outside.
I bought a heavy duty peddler I can use when I sit. I tried it right now at my desk and it isn't happening. I need a regular chair not one on wheels. I used it last night on sofa and it worked excellent. My plan is to burn 100 calories after each meal breakfast, lunch, and dinner. I still have to do my regualr excercise. I bought this to add to burning more calories in my day. I paid 10 dollars for it at a thrift store :)