For many years I have been using Titebond II almost exclusively, and to great result, so I thought that Titebond III would have to be pretty outstanding for me to switch. On the first project that I used it on, I was very impressed. In the course of building an arts and crafts inspired coffee table, I needed to glue up six relatively long boards into a panel (the table top). I appreciated two things right away with this glue. First, the long open time meant that I was able to work at a comfortable pace without as much hurrying and stress as that sort of operation usually induces. Second, I appreciated that this glue dries to a light brown color, which blended in well with the general color of my q/s white oak.
Of course, only having used it for building indoor furniture, I cannot attest to the waterproof nature of this glue, but with all other things - open time, bond strength, color, etc. - I am sold. Titebond III is a winner in my book.