I agree with Littlemisslozza that nipple confusion is often hyped and that many babies aren't affected by it, however I think it really depents on how set you are on breastfeeding.
With my first (DD) I just assumed that if you wanted to breastfeed you did and if you didn't you didn't. I wasn't expecting it to be easy but I was utterly unprepared to not be able to do it, which is what happened. DD had a fairly tough birth and was a bit battered and bruised so wasn't really interested in feeding for the first couple of days. I was advised to give her formula top ups on her first day when she had not really bf properly.
She was a big baby (9lb7) and I wish I'd have known about nipple confusion because I followed the advice and that was the beginning of my problems. Even though I did manage to get her back to exclusively breastfeeding over the course of a couple of weeks, her weight dropped dramatically and I was advised to start topping up again. Because of the top ups, my milk supply was affected. I got really cracked nipples to the point where I couldn't feed at all on one side so was expressing after every feed whild DH topped DD up with formula. We fed her every 2 hours for 16 weeks and I felt an absolute failure. Eventully DD completely rejected the breast and screamed blue murder everytime I tried to feed her and I cannot tell you what a personal rejection that felt like. Even typing this now is making my cry. I couldn't let it go and it affected my whole maternity leave. Nipple confusion was only part of the problem, but it was the one that stopped us in the end.
With DS, I was determined to give it another go, but not to beat myself up about it if I couldn't do it. Fortunately he had a much easier birth and took to it like a duck to water. My nipples were tender but no where near as bad as with DD and I knew where to get help. I tried him on a bottle at 5 weeks when BF was fully established but he wouldn't take one at all. I tried every different type of bottle and teat, warm, cold, fomula and EBM, me, DH etc etc. I even tried starting him off on the breast and "sneeking" the bottle in - he spat it out. He was EBF until 6 months and didn't take a bottle until 10 months. My babies are obviously one trick ponies - once they decide what they are having, nothing else will do.
Topping up also had a hugh effect on my milk supply. With DD I could only express 4oz in total from both sides, expressing after every 2-hourly feed. With DS, once my milk was established, I could express 8oz on one side in one feed! I had so much I donated it to the milk-bank in our local special care unit.
Sorry for the epic post, but I wanted to share my story because all the advice we are offered is, after all only advice, and only we can determine what is most important to us. So long as the baby is fed when needed and thrives, it is no-one else's business how or what they are fed. But the advice is there for a reason and your baby might be the one that they are talking about, even though everyone else's doesn't seem to mind.