when I was there about three years ago it was no problem. dollars were easier than euros. But situation in venezuela is fluid to say the least. So need up to date info from chris. My venezuelan friends say that things are a bit sketchy every where in the country now so really I would be checking other places that are definitely safer
Actually the " black market " ( or parallel ) exchange is about 75-81 Bolivars for 1 USD.
There are many students manifestations in the cities. The economical situation is getting really hard on this people ( inflation by more than 58 % in a year ! )
I don't know about Margarita but here in Adicora it is really quiet instead of the busy weeks of the " carnaval " and " semana santa " when the venezuelan crowds invade the site ( i do not recommend to come here in these two events. It is discusting !