"You must have a fantastic camera."
There's an apocryphal anecdote that circulates among photographers about a "socialite" complimenting a photographer's work, saying "you must have a fantastic camera." Later, the photographer returns the favor, complimenting the dinner she served by saying, "you must have a fantastic stove." (I’ve heard it attributed to Ansel Adams, perhaps to lend it legitimacy. I'm not sure he would have been so rude.) The obvious message is that when someone says this about our photography we should feel insulted and be condescending.
Photographers should know that most people do not look at photographs with the same critical eye as those who produced the image. (Some may count on that fact, judging from some of what passes as wedding photography.) When people make this statement they are expressing their appreciation of the image, even though they may not be able to articulate why they like it. They're ordinary people, not art critics. Chill.
If we silently roll our eyes when we hear this we are missing an opportunity to accept a compliment and maybe impart a bit of knowledge. By graciously saying, "Thank you. Let me tell you what I particularly like about this image" we may begin a dialogue in which we learn how non-photographers see our work and politely teach a lesson on composition and light.
Not to mention, we avoid looking like self-important jerks.