The problem is, back in the days, things
were great (economically) in West Germany. Now, Germany has 5 million people out of work and the national debt is through the roof. And in many cases, the money that is sent to the East isnt used very wisely. I.e. today most cities in the east are nicely restaurated, but they lack inhabitants becauses there is no work and people move to the West.
Also, people in the east speak a terrible dialect and the working habits they have acquired within 40 years of communism dont seem to work so well in a capitalist economy. I dont mean to say they're lazy, it just comes naturally when you work in a command economy. There's a production quota to fulfill, so you work out a plan, and follow it and theres no need to think about improving anything for like the next 4 years. There even was an employment guarantee in the GDR, so that's quite a contast to the working world in the west. (Though Germany is not as capitalistic as the USA, the labour movement is quite strong here, so for example it's nearly impossible for an employer to lay off a long-time employee over 50, etc.)
I still think the reunification was a good thing. But it should have been done differently. It was wrong to immediately apply western standards to all aspects of life in the east, i.e. health care, welfare, working standards, etc.
The GDR sure was in a mess in 1989, but it still was a developed country and one of the 10 biggest economies on its own. I think a slow, steady adaption process could have prohibited the de-industrialization process of the last years.