German dubbing is top-notch.

Some of the voice actors are so good that I was almost a little disappointed when I heard some American actors' original voices for the first time (e.g. Bruce Willis).

Here's what Vader and the Emperor sound like in German:

https://www.youtube.com/watch?v=8BC9daxWrL8

The only other country I spent enough time in to judge the quality of their dubbing is France. When I lived there for half a year, I was really surprised by the fact that their voice actors still mangled English words and names like ours did 50 years ago (turning a "John" into a "Jean", not being able to pronounce a "th" etc.). Not to mention what they did to the original trilogy (Yan Solo and Z-6PO, anyone?).

I hear that other countries have even worse dubbing. Is it true that in some Eastern European countries, all characters are sometimes dubbed by a single person?

Of course, I prefer to watch American films in English nowadays - no matter how good the German dubbing.

As for Episode I: No, the German dubbing doesn't make it any better... unless you consider being punched in the balls repeatedly by a German person to be a better thing than getting your balls busted by an American guy.

(Funny side note: Those annoying trade federation aliens speak with a French accent in the German version of TPM.)