I can't honestly say I've heard anything about them. I only know of Via Lingua there. Regarding Prague TEFL courses, I would take everything you hear with a grain of salt. There are over 12 TEFL courses operating in the city now. Out of the 1000 + teachers that are certified here each year, having a handful of unhappy grads is quite normal. Also, the competition is pretty fierce and some schools seem to employ unprofessional tactics. Overall, I believe that most courses do a great job.
If you are set on Germany, be aware of a few things.
Mainly, that if you not EU, it will be very hard for you to find legitimate work there.
Regarding the school, the best way to find information out about it is to ask for a list of students from the last 2 or 3 classes. Contact them and see if they are working and how they liked the course. This is probably the best way to see what the course is like. Actually, its probably the only way.
The Language House