The siren series are great but imo it doesn't have the appeal of SH simply because there's too many playable characters and their story is broken up in chunks too. The way they paced it is kinda confusing too with the jumping timelines. Honestly, felt more like a zombie game to me aside from the weird power that let's you see through the enemies' eyes.
SH feels more personal since you're only controlling one character. Siren feels like you're an outsider being told of the cast's struggles.
yeah, it is very different on the narrative part.
The way it evokes fear and horror it's very much like SH1 and 2 to some extent, i think it has more SH1 than 2 on it tho.
SH2 is more poetic and shit, but way less scary, i prefer 1.
The idea of taking mundane things into horror territory, the familiarity concept, it's very present on Siren and even more than SH i think, the games go as far as taking weapons from you , making you a child or a blind person and making you navigate everyday places now turned into nightmares.
It also has some of that subtext with characters showing their ugly sides and all.
I think the PS3 Siren game left such a bad impression on people not familiar with the games, that game is so bad compared to the previous entries, SH was no better at the time tho, truly the dark ages of japanese survival horror.
Edit: Also, Siren was making this whole viral internet add stuff way before its time, did you ever get to the Hanuda website and live feeds of the island on it? it was a different time and internet was way more misterious, it felt pretty authentic, like an OG ARG.