I can't help with a personal comment, as I do not use it. My two comments, which you can take or leave of course, are the following:
1. I have heard many serious writers speak highly of it via podcast.
2. I think often we like the idea of writing and the tools of writing better than we do the actual writing. If you are not writing everyday and making progress now using Word, Pages, Open Office (enter any number of options here), you will not be tomorrow after you have purchased Scrivener.
Or maybe it's just me that constantly distracts myself with stuff like that