Julius Bittner Der Bergsee

[Alan Howe]

Has anyone heard the 1911 opera Der Bergsee by Julius Bittner (1874-1939)?
http://www.amazon.co.uk/gp/product/B0006HSTUU/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A222B3K468LCHQ

[Ser Amantio di Nicolao]

I gave it to my father for Father's Day a year or two ago.  As I recall, his assessment was that it's pretty good until the end, when it just sort of dies.  I'd assume the idiom is German late Romantic, given what I know of the composer, but I don't recall actually establishing that with him.