Congrats and great idea getting a baby carrier!
I have 2 boys, and with the first one I used a sling-ez on and off. I may not have been using it correctly, but I didn't feel like it was truly "hands-free" (when used with a newborn) and I always kept one hand on the carrier. On the positive side, this sling was very discrete when I needed to nurse during an airplane flight.
With the second child, I ended up getting a baby bjorn. One word can summarize my feelings about the baby bjorn: Godsend. Baby #2 wanted to be held all the time, so he spent a lot of time in the Baby Bjorn. And it felt very secure, I could use both of my hands freely and never felt like he was going to fall out. For the first couple of days, my back muscles were a little sore from the "workout", but they adjust. And carrying around a baby all the time is a great way to shed some of that baby weight! :)