I purchased this PDF more for nostalgia value than anything else. It was the first D&D product I ever owned (bought from my local toy store in 1981!), and I cut my role-playing teeth learning the system.
The PDF is incredible quality. This is NOT a hasty scan of a faded and torn old archive copy, instead it looks like a brand new product! The colour cover is clean and vibrant, framing the memorable Erol Otus artwork. Inside the text is crisp and easily read, and the illustrations are faithfully rendered in their original B&W line art style.
The content is everything I remember. The system is presented in a clear and relatively concise format (having been revised by J. Eric Holmes, and Tom Moldvay). The intent was to remove some of the 'fear factor' associated with coming to grips with the rules and making it more accessible to a wider audience. The objective was certainly achieved, and this and its companion Expert rulebook went on to sell staggering amounts in what was considered a niche market.
Whether you are a nostalgia buff looking to recapture those early gaming sessions, or are genuinely interested in having a bash at D&D 'old school', this is a terrific place to start. Sharpen your pencils, crayon up your dice, and lets head to the tavern, there's adventuring to be done!