I have read much about how effective this spell is, but my experiences have not shown it. I do use it in doorways and similar places, and I know about the targeting techniques, but it just seems like it really doesn't hold anything for very long. Being that the mobs get a reflex save, then regular strength checks, which kinds of mobs can I expect to encounter that have low reflex saves and low strength? I am also pretty sure that once a mob has made its save, it no longer needs to make one when passing through the web again. I tried this technique in a doorway, and I did not see any 'save' indicator above the mobs head. I only ask these questions because of the disparity between my experiences with the spell and the overall positive opinion it receives.
Btw, most of my experiments with it were in Splinterskull against Hobgoblins with a level 4 Wizard with a 22 Int.