New monsters have been added, including the ground worm, which goes through three stages in its development, getting more powerful as it grows. New spells have been added, with a lot of focus on lower level spells, so that there is more variety and appeal for newer players. A frenzy is a scheduled time where for a limited period, the sky turns red and players may go on a killing spree and slaughter other players without any penalty. If you kill someone, you don't become labeled an outlaw or murderer, and if you get killed, you don't lose items or skills. The entire server is saved just prior to a frenzy and completely restored when it ends.
Frenzies occur about once every two weeks, and are announced in advance.
If you plan on logging off during the frenzy, just make sure your character was in a safe place when it began. Since that's where you'll be when the server resets, you don't want to be in the middle of a dungeon or the woods. The main goal of Meridian 59 is still correctly focused on the interaction between players. Most people are very accommodating, and are willing to help new players learn the ropes. I was reading a note that a new player posted on a message board within the game who got quite involved with his character.