If that's the cost of friendship, consider it paid.
All joking aside, I agree with the message. I almost signed up for app.net today, but didn't (after finally noticing the charge aspect (not gonna lie, didn't really look into it)) because it is NOT going to overthrow anything, let alone Twitter.
The warm sentiments of no ads is nice, but end-users don't give a shit. $50 is MONEY, free--adversely--isn't.
I'll be happy if people can prosper from app.net, but I don't see much happening there that didn't happen at google+.
You usually go to Soundcloud because you're linked there, it's not something that easily builds its own culture.