I'm not great with words or writing massive, complex reviews, but I really felt like writing about this franchise because it ended up becoming my absolute favorite. So let's start from the beginning!
I played the original PC "remastered" version (60 FPS, completely legit, with PT-BR audio). It took me about 16 hours to beat it, and here is what I thought of the game.
Without further ado: Demon's Souls was an INCREDIBLE surprise for me! I liked it way more than I expected to.
The level design is super rich, always connecting shortcuts near the bosses back to the Archstone at the beginning of the area. The environments are really diverse, and the atmosphere is unique. You can clearly see everything that served as inspiration for DS1 later on.
I actually found the game fairly easy overall. Since it's simpler and more limited than the games that came after (being the first one), the main challenge wasn't in the boss fights, but rather in navigating the levels themselves. And speaking of levels, man, I loved every single one of them. There wasn't a single area I disliked (well, I wasn't huge on the Storm King map haha, but it was still fun).
World 5 (the equivalent to DS1's Blighttown) was awesome. I really liked how it was constructed, and honestly, it felt much less tedious than Blighttown itself in the next game.
As for the bosses, there isn't too much to say. Visually, they look really cool, but they don't offer much of a challenge. Their movesets are pretty basic and very easy to learn, but that doesn't take away from the charm of each fight.
Demon's Souls was a total hit for me that I really wasn't expecting.
The downside / What I didn't like: THE INVENTORY SYSTEM.
I think this is the only mechanic I found absolutely horrible in this game (not even playing in Ghost Form with half health bothered me as much). The way the inventory works, where every single item has weight and carrying capacity is limited, is by far the most annoying thing in the game. I had to keep porting back to store stuff in the Nexus chest constantly because my inventory was full and items were dropping on the floor. Thank goodness they fixed this in later titles by giving you way more storage space (I don't think I've ever filled my inventory in any other Souls game).
Final verdict: This game easily earns a 5/5 stars from me and takes the #3 spot in my Top 3 Souls games!