I'm actually a F2P player, but I didn't bother playing it for a few months, missing some updates like Scream Fortress and Australian Christmas. But I started playing after a few of my friends started playing as well. After learning some basics and gameplay, I decided to upgrade to premium for hats too. XDDDDDDDDDDDD
The Scream Fortress Update was great XD
Two bosses to face against, its awesome. the Horseless Headless Horseman tears crap up! The only two things I hate are Monoculus, and the Gift Drops.
The giant Eyeball is a gun happy monster who fires CROCKETS everywhere and will kill you instantly. He jumps around the map every 5 seconds. However, he does leave a portal behind that will port you to the underworld, where every second you lose a bit of health. And if all the players don't kill it in enough time, he leaves.
And secondly, getting the paper masks. The masks are required to craft the Saxton Hale mask, which you need to unlock and achievement. So if you want all the achievements, YOU NEED THAT MASK. I crafted it, but sold it later for a hat. The problem is, THEY ARE ALMOST IMPOSSIBLE TO OBTAIN.
MOst of the time, other people find it. More than 10 people need to be in the server for it to spawn, and its a pain. It doesn't have set locations. At all. You can obtain the gift achievement in the Monoculus map. Its a little easier. But instead of a mask, you get a Haunted costume piece instead.