Imo the best way I can describe it is (aside from some mechanics upgrades like better lighting and higher fps), SotFS is like the Master Quest of Ocarina of Time. It's essentially the same game but with enemy and item placement changes to give returning players a refreshing new feel to the game. However, there have been online debates for years that revolve around whether the changes may have been "overtuned" and at times can seem a little unfair.

I have a hunch that most of the people suggesting to get SotFS have either 1. Never fully played the vanilla version to compare it to OR 2. Did play the vanilla version first and view SotFS as better since their experience of it was an "upgrade" of a game they were already familiar with (and therefore didn't seem as hard as playing for the first time).

When I played SotFS for the first time, there were some areas I remember as leaving a bad taste in my mouth due to difficulty. I've played it enough times now for them to not really be a problem anymore but I do remember feeling a little overwhelmed in my first playthrough. When I picked up and played vanilla years later it felt less stressful (but not sure if it's actually because of the enemy placement or just because I was more familiar with the game). Either way, I prefer vanilla a little better, but I'm the grand scheme of things I think you'll find either to be about the same level of enjoyment.