I get your complaints but I played Demon's Souls after all the other From Soft games (well, before Elden Ring) and I still love it. It has the most interesting world, by far - each of the worlds are unique and distinct, with their own character and it all makes sense. It isn't half-finished like Dark Souls 1, it isn't terrible like Dark Souls 2 and it isn't filled to the fecking brim with cathedrals like Dark Souls 3.
The levels are designed so that you are meant to handle everything between two archstones in one go. As a trade-off, these sections are relatively short compared to some of the sprawling levels in later games. Tiny narrow sections where you fall off with one wrong move are a staple of FromSoft games though, each and every one of them is full of those! Remember Blighttown?
What I do hate about Demon's Souls, and I believe it should have been done away with in the remake, is the Item Burden. That's just tedious - though at least in the remake you can now send items straight to Stockpile Thomas from anywhere in the world. Also, the tendency system, while original and creative, is way too obtuse and there are simply too many crafting paths with their corresponding crafting materials that you have to grind for separately.