Don't know if you got your card yet, but mine came in yesterday and it is exactly like I expected. You can load up from any account from the wallet app on your phone and (at least for me) the money was available instantly. Didn't matter if I loaded from a credit, debit or bank account. So now, I am taking my phone and google wallet card with me and that is it. No need for anything else, since I can just transfer money whenever I want from any source I want.
Benefit: I still get my reward miles and cash back with the credit cards that have those.