Reciting a prayer is like going up to your dad and reading a "heartfelt" request to him off a 3x5 card. It isn't spontaneous and consequently isn't sincere in the way conversation with a parent should lack pretense. Recitation of magic words is the sort of thing mystical religious people riddled with superstitions approached worship. It is primitive and ritualistic.
Terry, I tend to agree with you about the lack of personal connection that ritual (or recited) prayer involves. I happen to disagree, however, that it cannot be sincere due to it's lack of spontenaeity. Assuming for a moment that there is an all knowing, all seeing, benevolent creator of the universe who loves us and hears our prayers, I simply cannot believe that it is the order of those words--or the unique (or not so unique) arrangement that is important.
I believe that the validity and sincerity of a conversation between man and God does not hinge on whether the prayer is extemporaneous or recited, but only on the intent behind the act itself. For many, there is comfort in the recitation of an existing prayer--it is knowing that what you sincerely wish to say has been said well before, in a way that makes sense to you--and where one might struggle with the words to express what you feel, another has captured that feeling in a form that speaks to you. I cannot imagine that the repeating of those words is less beautiful to the ear of God than those that are more impromptu in nature.
When discussing prayer with a group of people several years ago, a friend of mine said something that has always stayed with me: She said "The desire to pray is a prayer in itself". I think that if one has the desire to pray, the intent to speak to God, it matters little the form the prayer takes.
But that's just my 2 cents. (Edited because my formatting was all sorts of wacky!)