Agree that it wasn't quite as good when it moved to BBC, but it might be that they were longish series and it became repetitive and a bit soapy. I did really enjoy the reunion special they did a couple of years back, probably 5 or 6 years now. Proved what a great cast it had, because it was a limited idea really, made great by good character actors. I think most of the cast made their names on the original series. Good scripts too from the excellent C&LeF.
Another series I've never rewatched so I might have to get series one sometime, I remember the unexploded bomb episode being particularly good. Oz was brilliant in the German series.