What was “the product”? They got a ton of attention initially but it really felt like that was squandered by the poorly defined message about what you were paying for — especially when many proponents reacted to early “it's like Twitter but open” stories by saying they were wrong and it was something else entirely, possibly only for developers.
The primary memory which I have of that era are people not wanting to pay for something which wasn't clearly useful, shrugging, and going back to Twitter where most other people were. By the time app.net finally launched the free tier the self-inflicted damage was already fatal.