Pros: easy on/off, long term use
Cons: can't face out
We've been using our Ergo (with infant insert) since day one. Our son loves it and, especially now that he is wants to get down and run more, it's great that he pops in and out so fast!
We did have a period where he wanted to face out and the Ergo doesn't have an outward position, but otherwise it's been in constant use. He's napped in there through many all-day events (I mean, he takes his naps while in the Ergo) and we often had times where it was the only practical way to keep him close for long periods.
I recommend the Ergo to all my friends!