I don't think that almost holding your vote share can and being established as a party with a staunch voter base, that will almost always get you above 5 per cent everywhere can be described as an "awful result", although the times, where there was no way to go but up, are over, hopefully.
It definitely is. The AfD is politically impotent and will never join any government. They will get their 10%, sure, but that's complete meaningless in the grand scheme of things.
For a party that wanted to 'hunt down' (Gauland) the establishment, that is (and must be) extremely disappointing. Especially as Germany is rapidly becoming more multicultural and socially liberal.