Some of it might be that I'm not a big fan of Hammer films in terms of horror, but I did greatly enjoy the campiness of the original Ravenloft modules. I have run them multiple times under different editions, and they were always great fun. But the demi-plane background and railroaded adventures of the 2E setting did little for me. It seemed like it was more fun for GMs to read than for groups to actually play. The two times I played in the Ravenloft demi-plane setting, the players had pretty much exactly the reaction I would predict.
I've also run gothic horror in some other systems, which I found good fun.
I think everyone responds to settings differently. For me, Ravenloft just resonated massively and I had no trouble running it (it was literally pretty much all I ran in high school and for several years after). I had long, ongoing campaigns. The ones that were more successful, tended to be based on the monster hunt investigations you could build using tools from the Van Richten books (but that was definitely not the only kind of campaign). Mostly I ran it with the player characters as outsiders (not as a weekend in hell, but as a campaign where the premise is they are from another setting and get pulled in). Occasionally ran it with them as natives (I personally found this didn't work as well for me, but I think that was just personal preference, not a problem with the premise itself). Ravenloft did suffer from some of the usual 90s problems with RPGs. But on the whole, I found it a lot better than stuff coming from WOTC in the 2000s.
The content was fun to read. I don't think it was as self indulgent though as other 90s RPGs I remember doing that. And the enjoyment of reading it, mainly helped fuel my interest in playing. If you look at the black boxed set itself, the domain entries are pretty sparse actually, so there isn't a massive wall of text to deal with there, but there is plenty of open space to add things yourself (I was always adding towns, villages, castles, etc). And the stock cards, some of them at least, did help simplify referencing some of the material. I basically read the black box in one sitting and was ready to run it that weekend. My first adventures were things from Book of Crypts followed by Feast of Goblyns, and after that mostly made my own adventures. There was an adventure site called House of Lament if I recall, and it was a cool premise but I do remember adding an enormous amount of content myself to make it more interesting (just details that helped out and a few new monsters).
Ravenloft works well if you start with the villain, or the threat. I found it was very easy to have long ongoing campaigns if I began there and worked around it. Also one of the cool things about Ravenloft is monsters were highly individualized, spells didn't operate as players expected them, the mists could mess with people...so you could have ten lycanthrope adventures back to back that were quite different, requiring different approaches from the players (same with vampires, mummies, golems, etc).
Obviously I can only say what worked for me, and what worked for me, might not work for others, but I truly had no problem running Ravenloft regularly and found it a lot easier personally than something like Forgotten Realms or Dragonlance (which I did try to run and wasn't as successful with)