I'm a huge fan of breastfeeding, but not for the reasons you hear most often. I'm not 100% convinced that breast milk is any better nutritionally than formula. (I suspect they both have their advantages.) I guess breastfeeding is cheaper, but as Tori points out, the typical analysis ignores all the costs of breastfeeding; it is certainly not free. It's more convenient at times, but it can also be a hassle when you have to pump and deal with leakage. I could go on...
What I love about breastfeeding is the bonding. I enjoyed it so much with Sammy. It was hard to imagine having a baby and not breastfeeding. There is just something wonderful about giving your child sustenance directly from your body. But it is also the most interactive thing you can do with a newborn. You spend a lot of time looking at your baby; it's not a passive enjoyment, but a time of active observation that allows you to get to know your child's personality just a little bit. You have to learn your baby's signals and your baby has to learn yours. When you both learn how to do it, you achieve a kind of symbiosis that is very fulfilling. For those of you who've never experienced it, I'd liken it to the feeling you get when you learn how to control a dog or a horse; when you both understand each other and work together, everything becomes easy and you experience the true joy of teamwork. It's also like the concept of flow, but between two people instead of just an internal state. Everything just feels right when you are nursing.
But with Sammy, I had no differentiation for my observations about bonding through breastfeeding. I had nothing to compare it against. I only had one child, and I breastfed exclusively. Not only that, but Sammy never even had a bottle of breast milk because I was unable to pump effectively. All I knew was nursing.
With Leo and Zoe, I've learned so much more about this bonding. Mostly, I've learned that my conclusions were right.
Since Leo was born bigger and stronger than Zoe, I was able to nurse him almost immediately. I can't remember the exact dates, but I think I began nursing Zoe at least four days later. I only nursed Leo once a day, but in those days I felt much closer to him than I did to Zoe. I had a relationship with him that was simply absent with her. I've been able to continue breastfeeding both children at home and to this day, I feel closer to Leo than I do to Zoe. That could be due to other factors, but based on that early experience, I think it has a lot to do with the breastfeeding. But they are only one month old and I expect that to change.
I've also bottle-fed both of them, and I'm surprised to find that the bonding that takes place with this kind of feeding is very similar to that of breastfeeding. You still get a lot of the interaction. Both baby and parent must pay attention and adapt to the other. It's possible that the only things missing are the skin to skin contact and the hormones. Adam never got to bottle-feed Sammy, and he is thrilled to be able to do so with Zoe and Leo. I asked him if he now feels cheated that he missed the chance with Sammy and he gave me a (friendly) sarcastic reply about how, yes, they just don't have a connection between them. (Adam and Sammy have just about the best father-daughter relationship that I can imagine and they are super-close considering that he is not the primary caregiver.)
So in the end, I don't think any of the bonding is relevant to future relationships. I find absurd the idea that, if you don't breastfeed an infant within 5 minutes of their birth, something will be forever lacking in your relationship. My relationship with Zoe is growing deeper by the day and just because it started out slow doesn't mean it won't catch up. And I don't think bottle-fed infants suffer from some kind of lack of love. Of course, I don't even buy attachment theory, so there you go. Breastfeeding can be a wonderful thing, but it's really just icing on the cake.