I just installed an anti-glare protector on mine. If I'm absolutely honest a little bit of me wishes I got a glossy one instead, it definately reduces the clarity of the screen. It took me 4 attempts to install one succesfully though (without trapped dust and bubbles) so it's staying on for a long time now.
I know alot of people say "you don't need it" or "my device is x years old and has no scratches". However, I tend to find these people have a slightly different definition of a scratch, which is basically "if i cant feel it with my finger, it doesn't exist". Problem with that is iPads sold on ebay as "like new, no scratches!" usually have very minor but very real scratches. I know the glass used on the iPad is pretty tough, but the coating over the top of it seems to be a bit more delicate.
My iPad has a few scratches, the worst one is a small 5mm long scratch on one of the black borders. I've actually grown to like it there because it's served as a reminder to treat the device with care, like take your watch off first! The other scratches are very small, very light, only visible under light, but they are there.