They have real effect. In Saxonia the NeoNazis are in the state parliament, causing a grand coalition.
In west Germany + Berlin they are pretty irrelevant. There chances ever to come to power on the federal level are zero, but when they get 5%, they could force kind of a permanent grand coalition, which wouldn't be exactly democratic in the long term. Der Amerikaner ist die Orchidee unter den MenschenVolker Pispers