I use paypal frequently. For low-end items it is downright convenient. For high end, it's too expensive. And, it is a myth to think you're being "protected."
If you send someone money via paypal, even if the money comes from your credit card, the risk of fraud is entirely on you. This is different than vendors which have an account with that credit card, and the issuing bank has recourse: If they agree with your dispute, they simply dun the vendor's account, and that's it. It's the power of the paycheck.
But if you send $3000 to Danny De-Man, for a purchase of whatever, and he takes the money--you're then at Danny's mercy. If he stiffs you, your credit card company or issuing bank will tell you caveat emptor. They don't have an account with him, you authorized the money to go to him, and that's the end of the story. He may not be able to do business on paypal again, but that may be okay with him.
I read over as many of the C2it terms as I could, and this same lack of protection exists. But if in fact you save on the exorbitant fee, then, yeah, it is a no-brainer (note that the site says that the credit card issuer may choose to charge a fee). If there's a 3% bite being taken out of my $3000 transaction, then it really costs $3090. If you save the $90, as opposed to not saving it on paypal, then that seems worth it to me.
Big thing is getting it to catch on. It'll be interesting, but I expect it to be a major competitor of paypal quickly, which has enjoyed a sort of only-game-in-town status for far too long.
Nick