For 1c-50c, both US and Ecuadorian coins are used. The $1 is usually the Sac. dollar, though I believe they've also been bringing in presidential dollars of late. $1s bills IIRC are not used much. I guess it's kind of like the 5DM bill in pre-2000 Germany, where the coin was preferred.
Small change seems to be hoarded for some reason, though, and having rolls of quarters and $1s goes a long way.