> whether Whatsapp can retain their users, due to it's novelty or despite the lack thereof.
WhatsApp's been around for years; not sure what novelty you are talking about. It's a very classic and straightforward user-base argument: do I know anyone who uses it? Yes, then it's absolutely worth the six SMS it costs me; no? Meh. I personally had it for years, on and off, simply depending (internationally mobile) friends asking: “Communicate via WhatsApp?” It's about as obvious to subscribe as a all-you-can-eat SMS plan.
I think we can agree on it's usefulness, but your concern was Whatsapp's novelty.
The part that's indisputable is the massive and active user base.
The real question is whether Whatsapp can retain their users, due to it's novelty or despite the lack thereof.