I would rather release the beta in more stages, after all, people forgot what Beta actually means and expect the app to work prefectly.
I want Viber to have more betas, closed ones, until it resolves all problems and makes it work PERFECT.
After that, release it for the masses, so it has such a huge impact that people forget every other app out there. That's how you make it successful. Learn from LiveProfile for example.
Apps like Whatsapp, Kik, Qik, even BBM and many others were the standards for a long time. LiveProfile was launched and in 5 days it had more users than all of those (ok maybe not BBM) combined. over 3 million users in 5 days, now it's already.... over the top for any up to be able to catch it up.
Do the same with Viber, don't "f.uck" around.