Its perfectly safe,..i met plenty who did it last year, but nish is right it does work out more exspensive on your own, but its no prolemo becuase when ever u head out u'll make plenty of friends with other workers who 9 times outa 10 have or knows someone with room @ there apartment.
When working out there last summer i stayed @ Hostel Horizonte @ 20 euros a night,..just to give u an idea if u shared with one more person it worked out @ 18 Euros a night.
but i ended up finding 3 other workers who had a spare bed,...and stayed there @ 60 Euros a Week !!!
I highly recommend doing it,...u'll have the best time of your life, FACT!!
may see u out there 8)