It would be easy to see Stillfleet's mechanics and mistake it for a standard roleplay experience. Its stat blocks, classes, and equipment tables will hold an immediate familiarity to anyone used to playing older and more traditional TTRPGs. But where Stillfleet shines (aside from the art and layout) is the intricate web of fruitful voids it produces (you can drill down into any aspect of the game and play with the concept for hours), and the truly wild characters it gives you (every class and character feels uniquely overpowered. While you will find yourself in the occasional situation that just isn't your character's forte, the ability to burn your grit pool on any action you choose gives you the agency to produce a truly terrifying or deeply emotive scene wherever it suits the narrative).
The quickstart rules are okay. But I'd recommend joining the patreon and getting Wythe to run games for you (plus having access to all the in-production material for the full version).