On the flip side, if you loved your job, your coworkers, your boss, the cappuccino machine, everything about the place, don't write page upon page waxing rhapsodic about all that you're giving up by leaving. A brief, heartfelt compliment to the company, or a thank you, is fine.
The Thank You. Next, it's always a good idea to thank your employer for the opportunity, describing some of the key things you've enjoyed and learned on the job. And yes, this is true even if you're thrilled to be leaving. Remember__you may need these people for a reference down the line, and leaving things on a good note will leave a lasting (positive) impression.