That is about it for the content, believe it or not; it is direct and straightforward without any fluff or nonsense. You are simply covering each detail so the seller knows exactly what the buyer intends to do. Having an informal letter of intent also allows for easy negotiations.
For example, there may be soil contamination in which the buyer will not want to purchase the property and will safely option out of the non_binding contract. Or, perhaps the property is in a lot worse condition than originally thought, causing the buyer to negotiate a decreased purchase price.