I have to disagree. My SNG was invaluable with a kid in school and an infant born in the fall in the midwest. I pretty much used it for school drop off/pick up only. It was great to be able to have the baby covered in the car seat and just pop it on the SNG for the five minutes we had to be outside. It was not my main stroller, though.
Maybe there should be a disclaimer about using it for extended periods of time.