Grimm seems like no other RPG I've encountered before.  I'm curious: what do all of you feel are the best aspects of this particular game?

 The simplicity. I was able to sit a friend down and just go along doing a quick little story I wrote up, and then went straight into making stuff up on the fly because we enjoyed it so much. He was quick to learn and being a narrator, the longest part is just reading about the grimm lands. The simplicity also allows for players to be able dream up complex ideas and not have to worry about being bogged down by rules. It's either increase the difficulty of the role, or require certain traits to be expended in order to accomplish it. 

 I gotta agree with Laughmask on this one. Less is more!

Simple rules and Linear d6:

1. Easy for players to learn and play
2. Encounters are simple and fast (Quick pace!)
3. Less time rehashing rules and more playing!

I also find Grimm a refreshing game in terms of story and tone. Running around as kids in a twisted world is interesting, fun and scary. Players have to change their mindset when they play; you can't simply run at the Ogre sword brandished, you have to compensate for the fact you're vunerable children! The horror and twisted fantasy themes are also lots of fun.

Imaginings add depth to the game, giving power to players to create unpredictable outcomes and solutions. These things are what I believe enables GMs to create an engaging and fun experience for Grimm players.