Offering a "funky" youth brand is standard practice for prepaid mobile operators: Optus does it with Boost and (to a lesser extent) Virgin Mobile, while Red Bull is a similar offering on Vodafone. ONEmobile ploughs the same furrow, but under the cool branding is a very ordinary offer indeed.
I am manifestly not part of the ONEmobile target market, so offering a site which says "My Deets" instead of "account" and "Nuffies" instead of "Help" leaves me cold anyway. Having an Android app which lets you recharge is neat but, ultimately, not essential. But what really horrifies me are the rates charged by this service (which also uses the Optus network, though it isn't owned by Optus).
Take the $19 cap. While this includes $100 of "credit", the call rates are high: a 40 cent connection charge and then 90 cents per minute or part thereof. That means $1.30 every time you make a call. Internet browsing rates on that plan are also high (30 cents per MB or part thereof). Some of the other plans have cheaper call rates, but much less credit.
It's no effort at all to find better value. Using the same network for prepaid customers, Amaysim charges 15 cents a minute with no flagfall, and data at 5 cents per MB -- a much better deal. Even Boost Mobile (which I rarely single out for offering value) has much better short term deals. Definitely one to avoid.