The problem isn't the swing itself, it is how you use it and the huge amount of different advices you will get.
There are people who are pro sleeping bag, there are people contra. There are people pro rocking a child to sleep there are people contra. But at the end of the day it is your child and you need to do what you think is best for your child.
From my experience a soft rocking motion helps calming infants a lot. You start doing it naturally as soon as you have a child laying in your arm. Make sure the swing isnt rocking too hard or can tip over by it. Watch the child and never leave it unsupervised in the swing. Maybe a big cradle is the better option for a child this young?