Recs.
Updated
Specs
Pros
Pro Focus on the game, not the character sheet
Basic D&D is 6 ability scores, a few skills, a character's saving throws, some equipment and, if a spellcaster, some spells; and that's it. This makes the game more about what's happening in the game rather than an exercise in firing off various powers on your character sheet.
Pro Vibrant online community
As with AD&D 1st Edition, Basic/Expert D&D is one of the favored editions of the Old School Renaissance community, who regularly offer wildly creative material for it and have published several retro-clone editions, all of which are currently available online either for free or for low prices. OSR blogs on Blogspot and Google+ communities serve as sources of considerable materials that can be used without modification for this edition, and some of these materials break far away from the "standard vanilla fantasy" flavor of Wizards of the Coast's publications.
Pro Character balance
Warriors with weapon mastery and wizards with spells at higher levels feel more on par with each other than in other editions, where the wizards easily overshadow the warriors of the party. Magic is the best in other editions whereas in BECMI they had a place in the party and it was usually in the face of some monster.
Pro Lamentations of the Flame Princess
Lamentations of the Flame Princess is a horror/fantasy game (not for kids). Fully compatible with Basic D&D material, it features a few non-breaking adjustments such as a vastly simplified encumbrance system.