First off, build 11 is a large mod incorporating all of the mods released at publication. It came out sometime last spring. As you can tell, there were 10 previous builds. Somewhere around build 8, if I recall correctly, the build functioned like a patch as well. You see, Akella/Bethesda never patched the game and the out of the box version is very buggy. If nothing else, the build patches those issues.
Go here to read all about the build: <a href="http://forum.piratesahoy.net/ftopic2378.php" target="_blank">http://forum.piratesahoy.net/ftopic2378.php</a>
As for playing the game in its out of the box form. All I can say is that `half-way` through the game I went online to see if there was a patch. I had played the original `open-ended` Sea Dogs (POTC was originally Sea Dogs 2 until it was bought out by Disney and rushed to publication six months before it was ready... hence the bugs) and I expected POTC to be somewhat like the original. I was wrong and was very disappointed. Build 11 makes the game much more like what we all hoped. If you played Sea Dogs, I would recommend starting with the build.
However, at the same time, perhaps the only way to appreciate the build is to experience how bad the original was.
My gut reaction, however, is to tell you that any time you spend playing the game without the build is time wasted.