Well. Interesting. I guess we can classify that as a "Historical Curiosity."
Certainly an early example of the "let's kill everyone just cuz we can" sub-genre.
The locations and sets were wonderfully New England Gothic. Loved the abandoned houses and tunnels and the empty pool and so forth-- did the series ever explain why the Collins Family let their property deteriorate so badly? I seem to remember one TV plot that involved somebody living in an entire wing of the house that had been closed off and abandoned.
Unfortunately, even beyond the fact that it was disconnected from the TV series, this movie was pretty weak. The script was borderline incoherent (what exactly was
the point of that opening sequence with David?) and Dan Curtis was not exactly at his directorial best. And there were a few inconsistencies along the way: Barnabas seemed more worried about the tiny cross on Maggie's neck than the big-ass one hanging over the bed. And I think there are at least three new vampires out there somewhere that were unaccounted for.
It's too bad they didn't write something that was consistent with the show, like the producers of Batman
did around the same time. Oh, well....