Revise it so it's only the least bit indulgent. It will set you apart on paper and add an extra benefit for the recruiter. They'll have a fascinating anecdote to pass around at the water cooler. With everyone else using copies of examples of good cover letters, your custom cover letter may make you a small notable before you show up. Then try your cover letter out loud. No one else will read your letter the way you do. They're all used to reading from the same tired resume cover letter format. To discover how other people will understand your letter, put it through each of these three steps.
For you to be able to make an effective cover letter, you should be able to follow at least the basic format which should never fail to address three general issues: 1. First Paragraph _ The reason why you are writing. 2. Middle Paragraphs _ Facts about what you have to offer. 3. Concluding Paragraph _ Methods for you to follow_up