I cannot justify suggesting Demon's Souls... albeit great, the degree of frustration I felt with it out-weighed the "fun". It all ended for me on a bad note when I saved my game in a relatively impossible scenario to survive (do to my own idiocy).
Demon's Souls is not fun in the sense of your typical RPG that's enjoyable and engaging. Demon's Souls goes more for what Survival Horror games did back in the late 90s to early 2000s before they shifted their focus in the mid-2000s (out of necessity more than anything).
That said, I know that is risky to recommend Demon's Souls because it can be too much but once you can get into the flow and logic of the game everything just comes together really well.
Is a game that I would say is at least worth checking out.