C&C per req:
danjchau is spot on with his comments, however I would add the caution that that you want to be careful how far in each direction you modify your key exposure settings (Shutter speed, apeture, ISO). With a subject of this nature, you want to shoot fairly close to wide open to minimize the depth of field. You do however want to make sure you get it in the right place. You've done that; the spider and surrounding web is sharp.
The composition isn't ideal, however understanding the limits of your lens as you mentioned, it's not bad. With subject like this try, when possible to shoot either straight down on them, or with your lens axis parallel to the surface of the web for the most dramatic image.
With respect to your question of bokeh: Don't confuse bokeh with background. Bokeh a term used to describe the characteristics of the out of focus areas on your image. At least on my less than stellar work monitor, I really can't get a sense of the bokeh at all, I will say however that the background is rather distracting, being too sharply focused and of several different colours and textures.
Ideally you want as smooth and monochrome a background as you can, so that there is nothing fighting the subject for the attention of the viewer's eye.
Just my $00.02 worth - your milage may vary.
~John