Direct aisle access is the kind of seating arrangement in which every passenger can get in or out of her/his seat without having to disturb an adjacent passenger. This is especially important in business class on long-haul flights, like flights to and from Australia, where sleep is important. The advantage of this seating arrangement is that one is able to sleep in peace and serenity while an adjacent person can get up and move around without facing the problem of waking up someone else.
Read the full article here for a comparison of business class seating configurations:
Why direct aisle access is so important for a business class seat