Well, I don't think I've wrote anywhere that I agree with the review, its results or that people should switch or make their decision based on the review.
But letting people know someone compared these services and wrote something about them from experience might be helpful to some of them. That is all.
Btw., I use Digg almost daily, most of the other similar services I don't care about, because the layouts of those are just too cluttered.
I suppose that's one of the reasons why some sites are so popular - Flickr and Google are fairly plain, almost any user who's not impaired in some way should be able to orientate on them pretty fast.
del.icio.us - horrible

, but many don't seem to mind the clutter on the main page.
Stumble upon - hm, just might start using it, although it seems to be just another Digg.
Then again, sometimes it's the content and not the looks that sells the product. Like Tech Republic - there are almost too many links on every page of that site, but it's a pretty decent resource.