I've worked through a number of language tapes, both for German and other languages, and Breakthrough German is one of the worst I've ever encountered.
For starters, the primary narrator of the tape struck me as arrogant and condescending. But worse than that is that the program does little to aid retention of what's presented. There are few opportunites to repeat what you've just heard and no follow-ups to confirm that you've said the new term correctly.
On the positive side, some of the dialogues on the tape appear to be genuine, real-life conversations that have been (surreptitiously?) recorded.
As alternatives, I'd check out Pimsleur (very expensive but excellent) or Living Language.