not if you wear protection. When you get the right stance you're crouched a little bit forward so it's actually quite hard to fall backwards and hurt your back/bum.
Even if you aren't going to wear full safety gear and helmet I'd say wrist guards and knee pads should be essential, and you can wear them under clothes (or if you're wearing black they're not obvious even if over) if you feel self conscious.
A pp suggested roller derby classes as being good even if you never want to play because they teach you how to fall safely, but you can get it from youtube as well and then just practice in your living room. Basically if your stance is good you don't have as far to fall anyway, and if you fall forward onto your knees the knee pads take the brunt and you shouldn't hurt your wrist/face/anything else. Ideally you should have the control to turn it into more of a slight skid than a direct impact crash which also lessons the impact. Sometimes you can use the toe of your boot to slow you down as well (although if you have fancy boots get toe protectors!)
When I'm out I usually do a deliberate semi-controlled fall at least once, not only is it then muscle memory if you do a not-deliberate one, it sort of takes away the fear/embarrassment of falling for real - I've actually never done so when outside (have indoors).
Because of people being around, rougher terrain etc you rarely go that fast.
Practice getting back up again as well -it's actually surprisingly easy.
You could trip and fall and break your wrist just walking or jogging and wouldn't be wearing wrist guards, so I don't worry too much.