Have you ever had a choice to make and when you finally decided, still felt some doubt? This is very human, and has been studied. In fact, the more options you had to choose from, the less likely you are to be satisfied with the choice you ultimately make.
One of the earmarks of a good customer experience is validation for your choice. Let me give you a good example, and one that didn't quite hit the mark.
A good example
I've been looking for a folding chair where I can put my feet up. We used to call these a chaise lounge, but now they don't fold, weigh a ton, cost a lot, and take up a lot of room on the deck. I wanted the old fashioned kind. After ages of looking, I finally found one in the camping section of Wal-Mart. At the checkout, the clerk said "My friend has one of those chairs, and they're great!". I instantly felt validated in my decision.
Not so good
In a good bistro recently, I asked about the Pad Thai... would the server recommend it? The server assured me it was excellent. After I ordered, he said, "Guess what the main ingredient is, in Pad Thai sauce?" I was trying to think of tamarind, but persimmon was what came out. "No", he said, "It's ketchup". It was an awkward moment. I didn't change my order, but wished I had. My dining companions were horrified. In trying to be friendly, the server had botched the validation thing, and pretty much took the fun out of the meal. Why, oh why hadn't I ordered the lamb curry like everyone else???
Why is validation important?
Being overwhelmed with choice is not the only thing we are working with here. We are also working with the Peak-End rule, initially hypothesized by the great Daniel Kahneman. We judge an experience in memory by the peak (either high or low) and the end.
This is why we have the saying, "you're only as good as your last [...]" We know that the last part of any experience is the part by which we will be evaluated. The last muffin or hamburger. The last encounter. We know this, even though we aren't as clever as Daniel.
So why let your customer leave the experience feeling uncertain or doubtful? Tell them what a good decision they made. Give them a little validation. You'll both benefit.
For a good explanation of Daniel Kahneman's Peak End Rule, check out this Wikipedia entry.
For an excellent book on the science of making choices, check out The Paradox of Choice: Why More is Less, by Barry Schwartz.