Hi Chillidog,
I've attached a photo from my Galaxy Ace. The scratches are pretty visible in the flash. Number 1 causes a single line colour distortion, like a half-inch long rainbow on the screen, easily ignored in general use but you can make it out easily when you go looking. All the other scratches are invisible in operation. Scratch 2 is noticeable to the touch. Run your fingernail along the screen and it catches in crack 2.
I've just applied a screen protector. Notably, when giving it a thorough clean I could see the swirls of the pen; what I understand to be microscratches. I'm of the opinion that the pen and/or eraser does actually scratch the screen, although maybe not to many's perception. I do not think my significant scratches are caused by the S-Pen. They are too extreme. I think one of the kids I teach took something to the screen they shouldn't have when I was out of the room. But I do think a screen protector is in order.
The one I've just applied is a GreatShield Matte. It eliminates the reflection and the scratches. The screen doesn't look as classy, but it does look clearer and without killer reflections or greasy fingerprints so obvious. The pen feeling is very different. The S-Pen encounters a lot more resistance. It's still very usable though; will just take some getting used to. I've also just glued a piece of felt on my additional S-Pen's eraser end.
All in all, I think the screen protector is recommended for the Note. I don't think Gorilla Glass is as immune to scratches as some might suggest. I have to say though, don't be discouraged by scratches. There's no better touch device IMO. The pen is the most functional addition to computing since the invention of the computer IMO. It turns a tablet into electronic paper. Handwriting can be real, rather than having to go through dubious gesture tracking. Autodesk's Sketchbook Pro is superb, and I'm hopeful ArtRage will get an Android port. I also prefer using the stylus over finger a lot of the time. Having a chunky finger in the way of the screen is an obtrusion. I've been playing Puzzle Quest 2, and I automatically pull out the stylus to play it rather than use touch. Get yourself a screen protector (probably good advice whatever phone you get as a cheap protection, because glass is still a little vulnerable no matter what brand it is) and enjoy the flexibility of the machine.