Why are they attacking Firefox instead of Chrome? It seems really weird.
My guess would be that Firefox users mostly consist of people that know enough to not use Chrome or a Microsoft browser. And an ad won't change that. Chrome is the new IE as far as the default that everyone uses, so it would make sense if they targeted them.
"Get the same browsing experience with better integration with Windows." (That's probably not true, but this is advertising, which never stopped anyone.)