A lot of people read The Art of War to gain insight into business competition, inter-personal conflict, etc. Personally, I think it is most interesting as an actual treatise on warfare, statecraft, and tactics as originally intended. Comparing the tactics and outcome of various battles and wars (past and present) to Sun Tzu's advice demonstrates that he generally knew what he was talking about and many (most?) of his principles still hold true.

I have read two different translations of this work. The first is the classic translation by Lionel Giles. This was the standard English translation for decades. It is easily understandable, but it is probably much more influenced by Western thought/turn of phrase than some newer translations.

The second translation was by Thomas Cleary and had the text interspersed with commentary by other ancient Chinese generals and philosophers. This translation made a serious effort to preserve the ambiguities present in the original, giving it a much more Eastern flavor. I can't vouch for translation accuracy since I can't read the original, but Cleary sounds more authentic than Giles.

The commentary sections sometimes gave insight into how "Master Sun" was understood by others over the next few centuries, but sometimes it was just a tedious unimaginative rephrasing of the original. On your first reading of The Art of War skip the commentary; it breaks up the flow of thought. (Also, don't bother with the 60 page intro unless you really want to hear the translator pontificate about Taoism for 50 pages while saying nothing that you can't pick up from the book itself)

If you are interested in diplomacy, espionage, military tactics, etc. this is definitely a great read. Next time you watch a war movie or play a conquer-the-world type game you'll find yourself thinking in terms of The Art of War.