I used a Moby wrap for my son for the new born period, and then I got a Maya wrap for Christmas when he was 3 months old. We tried it out and never went back to the Moby!
The Maya is SO easy to use. It's easy to put on, easy to adjust, and easy to get the baby in and comfortable. I watched all the tutorials on the Maya website.
I used this ring sling from 3 months until about 9 months when my son was over 20 pounds and it was too much for my shoulder. I was SO sad to not be using my Maya anymore. We switched to the Ergo at that point and that's what we are still using (at 18 months).
My son was able to nurse and sleep in this sling when we were our and about and that was great. The 'tail' was nice to drape over his head when he was sleeping.
I did end up using it 'backwards' when nursing. My son's head was on the ring side, rather than his feet on that side. It was comfortable for us, though.
He wasn't comfortable 'sitting' in it looking forward, we never did that.
I do keep this in the car, now, and in case I forget my Ergo I can wear my son into a store or something. But at 25 pounds I can't wear him in this carrier for very long. I can wear him in the Ergo all day long, though.