The 70-300's is not build so badly. It is pretty much the average Canon prosumer built... certainly not L. I prefer to bring a cheaper, poorer built lens for travelling, which is why I dumped the 70-200 f/4L IS for the 70-300. As for the infamous portrait issue, there is no need to lose sleep over it. Just bring it to the Canon service centre, and they will strip out the entire inside of the lens and swap it with a new version... thereby solving the problem. Even if you have a very old 70-300 with this problem, Canon will service it for you... for free... and you practically get a new lens (on the inside) after this.