I actually have a Shounen Jump sub with Viz, and came here to check out how fan scanlations compare... The fan translations are better, they often actually have color, and they make fewer translation mistakes and don't make arbitrary localization changes that don't make sense like random accents the original characters didn't have. Fan translations also don't censor anything either... so once again, "piracy" provides a better quality product than the official for-pay English releases.
Also, the reader is much better and more customizable. I've paid to read dozens of chapters on Viz, and after comparing their product to what's available here (and sometimes elsewhere on the net) I wonder why I bother. Don't get me wrong, I'll continue to keep paying as a monthly sub is cheap, but I'll probably give "feedback" about this.