I very much like the shallow depth of field here. The limited focus aims my attention to exactly what you consider the point of greatest interest. What I might recommend to strengthen this image is crop your image to limit distracting elements and to create additional lines that enhance your composition. The human eye tends to gravitate towards the brightest point(s) in an image. The extreme background of your image is quite bright. If you experiment with various crops of your image you'll find that omitting that background allows the in focus knot to stand out even more.
Your comments are much appreciated. I think I agree with you on this, my only concern being that the removal of the bright patch at the top of the image may make this photo less appealing when viewing at thumbnail size (and thus less likely to attract any critique)