Yes, us .ca'ers should all be using it.
I like Interac as opposed to paypal for a couple of reasons:
1 - the cash is there - no need to worry about credit card chargebacks down the road.
2 - no need to consider the processing fee
3 - Paypal's exchange rate sucks. Even though I have a USD account at TD, Paypal insists on converting to Canadian for me when I want to transfer out my funds.