While I do feel bad for most of the early, well-developed supporting characters that get turned into "mincemeat" later, I don't necessarily dislike what the DS writers and Dan Curtis did to them. Don't get me wrong, I really enjoy the early storylines and people, but if you look at it, Dark Shadows went through several different "phases" as it progressed - from the atmospheric semi-non-supernatural Pre-Barnabas episodes, to the insane 'out there' plotlines of the final year. It was a fun ride that changed course every few months/weeks. Stephen King described DS as a "Mad Hatter's tea party," and I think the show has that distinct reputation partially because it got wilder and stranger as it went along. IMO, these shifts were organic and part of the show's charm.
For me, the best way to enjoy DS is to think of it in terms of sections in an anthology. I enjoy each section for what it is. Some sections are better than others, depending on your preferences, but once a DS phase is over it's over and you get to enjoy a new, usually crazier, phase in the development of the mythos. Some aspects of the prior phase get left behind, while new aspects become more prominent.
I think this is why some fans of the show actually tend to complain about it a lot, or dislike large sections of the series. There are so many episodes, and several different shifts in the story. Some folks dig the whole series, while others only like certain sections, and despise others. It's an interesting phenomenon, and I wonder if this is the case with other long-running cult shows. I'd guess something like Dr. Who, which spans decades, probably has the same issue in terms of "phases" and fans who detest certain large segments of that series' storylines.
~Penny Dreadful~