If you don't know, many Guitar Hero 3 users complained when it was discovered that GH3 on the Wii was recorded in Mono, rather than Stereo. Activision stepped up and offered to upgrade the game, and replace the discs for free.
Not only is Activision fixing the Mono problem, but they are adding downloadable content. Did I mention they are doing this for free? The only caveat is that you have to send in your disc before Activision will send you a replacement. This is made clear on the website, and was made clear to me when I called to register.
As far as I am concerned, Activision has not only done the right thing by offering to replace the game, but they have gone above the call of duty by adding downloadable content to the game. The whiners at Consumerist have no right to complain, and should be glad that Activision is the kind of company that will not only do the right thing, they will go a step further. If it's so traumatic to give up playing the game while waiting for the new disc, go buy another one, or keep what you have. I mailed mine today, and don't mind waiting for a freebie.