I'm living in a "Eingetragene Lebenspartnerschaft" (it's in some parts similar to the heterosexual marriage, in others, especially adoption, reproduction and tax rights there are big unjust differences). My wife gave birth to our son two years ago and we are both legal parents to him (since 2005 there is the possibility of adoption in "eingetragenen Lebenspartnerschaften", it's similiar to adoptions possible for step parents).
We never experienced bad discriminations. Sometimes people look or ask biased questions. But most of the time we get positive reactions.
To sum up, to live as a lesbian in Germany is not causing any big problems, but I admit not every thing is perfect yet.
Anyway, if any of you planing on visiting oder living in Germany, being gay is usually no problem.