The first From Software game I've played was the long box version of King's Field on the PSX, then Armored Core 2 Master of Arena. I've purchased most of their Armored Core series, King's Field 2, Shadow Tower, Eternal Ring, Evergrace, Forever Kingdom, King's Field the Ancient City, Demon's Souls, and Dark Souls. They were always a good developer in my opinion, but their adventure games weren't ever amazing until Demon's Souls. Their adventure games were always okay or good. Most Armored Core games are good, though I feel Armored Core 5 is meh. Worst in the series.
And yes. Sony has made FromSoftware the well respected studio they're known as. Most of their games have been exclusive to Sony since the PSX. So they're where they're at because of Sony, whether or not you want to think of the reason as Demon's Souls or not.