A LOI is typically used as a "starting place" for negotiations on a property. Generally a LOI will be followed up by a formal Purchase Agreement after the terms are settled on. This may or may not be the case in your area, but is a good use of the two documents.
In fact, some experts have called the LOI a document whose use is primarily advocated or promoted only by amateurs and marginal dealers or "joker_broker" types in the crude trade business, especially the overzealous sellers' agents and brokers in a desperate hurry to land some buyers. Mr. Ziad K. Abdelnour, President & CEO of Blackhawk Partners, Inc, a New York_based advisory firm to traders and suppliers of metals, minerals and crude oil commodities, calls the LOI document something that is primarily "used out on the Internet by inexperienced traders," and by "inexperienced 'intermediary seller' who is claiming to be the supplier."