I had the Ergo and I resold it. There were things I liked about it, but the bad outweighed them. I may be in the minority, but I'll share my experience. My son was 12 months when I got it, and he's 18 months now. I only used it for a few months before deciding it wasn't for me.
First the great thing about it: NO neck or shoulder pain! None! I always get shoulder pain and neck pain with baby backpacks, no matter how expensive a brand. And the Ergo was great for that.
The cons: The Ergo is designed so that the baby is down low on your back (like a piggy back ride instead of up higher over shoulders). My son hated that. He couldn't see anything except my back. And the baby is tucked right against you, so I found it hot and sweaty for both of us. But the number 1 complaint I had was that it was VERY difficult to get him in and out by myself. There are extensive instructions on it, and I think it would be easier now with an 18-month-old or older, because they could hold onto you better when you're putting them in, but at his age at the time, I couldn't get him to hold onto me and hold his own weight to get in. With two people it was no problem, but even with practice, it was almost impossible for me to do it alone. I wanted to use the backpack for lots of errands alone, so that didn't work for me. If you'll always use it with another person, or your child is older than 2, it may be easier.
Good luck deciding! Sometimes you have to see for yourself what works! I can't remember where I ordered mine from, but they had a 3 month money back guarantee, and I used it with no problem.
