Uh...
1. Make purchases on your credit card as you normally would
2. We deduct the amount from your checking account each day
3. At the end of the month we pay your credit card bill
4. Sit back and relax! We got you covered.
Letting someone else skim the interest for something I could do myself just fine?
There's no difference I can discern between this and "auto-payment in full every cycle," which is how I normally leave my cards, unless you can't cover your expenses at the end of the month.
It seems like the "sell" is that if you're using debit cards (I guess to prevent you from spending more than is in your account?), you can have the same impact with credit cards and still see the money disappearing out of your account daily.
I don't use debit cards unless I have to in the first place (the nuisance level of my debit card being stolen and account being drained is potentially higher than for my CC balance being run up fraudulently), so I'm apparently not the target market here...
It's not something I see any reason to sign up for, unless there's something massive I'm missing in how it works or what it offers.