I commend the plugin author for taking the initiative to create this much needed feature. We have this plugin integrated into our themeid responsive theme.
After researching several responsive and mobile themes, I found it actually shocking how rare it is to actually find this feature. I'm surprised it's not a standard for responsive themes.
When using mobile themes in the past, with no opt-out option, we've received several consistent complaints from site visitors. We learned, through lots of trial and error, that people often like to control their own website experience, not have you control it for them. If you think about it, it makes sense.
I was easily able to install the plugin, even in a multisite environment. I choose to have a simple link show, instead of the standard button, which was very easy to do in the css sylesheet.
There are other projects and scripts out there "claiming" to accomplish what this plugin actually does, but after struggling with about 5 of them, I was about to pull my hair out before finding this solution.
Maybe it's a bit extreme, but I delayed the launch of our responsive site on the completion of this plugin. I just don't like the idea of hijacking the experience of our site users and not giving them the option to view our site in the way which they may already prefer.
Our website has a program for monitored online visitors (for chat support). Just the other day, when I glanced at the online visitors, I noticed that 4 out of 15 users were choosing to use the responsive opt-out feature. There's the proof!