I always thought the ads ("special offers") were incredibly unobtrusive. I even proactively chose to work on that team after having owned a kindle because I thought it was such a good example of ads done well. The ads suck on the kindle fire devices, but what else is the screen going to be doing when the device is off?
You can pay $20 to remove it, right? A $20 Kindle is still a pretty good deal.
If you have an ad-supported Kindle and talk to customer support, they will disable the ads for you, for free, no questions asked.
I honestly keep the ads because I hate the non-ad wallpaper. Its so boring and generic. Now, if Kindle had an option to have the wallpaper be the cover of the book you most recently had open, that would be a game changer.