The birth control shot

Is it safe? I have my mom & sister constantly trying to pressure me to get it & my doctor saying it would be great for "some one like you" I don't trust him. My SO is not a fan of the depo shot because I'm a very unique person- I'm open to telling why if anyone is curious- and he says he's heard some bad things about it. 
I don't know if my sister is trying to be nice or trying to screw me over. (She has kids & was told no more or it could kill her & she likes the attention that having the only kids in the family gets her). My mom thinks that sence it was great for her & my sister it will be great for me since I'm "just like her)
Honestly I didn't think the shot was used 18-20 years ago- I thought it was relatively new. 
Sorry I rambled- can anyone tell me anything about the Depoprevara birth control shot?