At least 4 people on HN had the same instinct, myself among them. HN is definitely a more technical cross section of the internet population. Anyhow, yes, it was a .5 second instinct to interact with it and then I figured it out. Not sure if that constitutes a negative UI experience or not, but it IS an issue. Hell, maybe there's some psychology at work that makes me want to download it to get the ability to interact! Who knows!