Novarium is first off one of the most beautifully put together games than I have enountered in a long time. While this is superficial and largely unimportant it is worth mentioning up front. The art is amazing and the layout is eazy to read even on a computer screen.
It is the simple, elegant rules system that is both easy to learn and easy to follow. This is both a major strength and a minor weakness. It makes play easy and keeps things from bogging down in overly complex rules. On the other hand the system feels almost limited by that as well. There are no really complex combat maneuver rules presented in the rules. This leaves a lot of interperation up to the GM as far as what difficulty dice something should use.
The world is well put together. The design elements are solid and while the history could be epounded on a little more it's really not, especially for a free product, all that much of a detraction. In a sense it also helps with the dark ages feel of the world. The culture and religion are well documented and color the enite volume well which only serves to make the setting far more interesting.
The simple, class based character creation system is the only major detraction from the system. It is definately limiting in what a character is. There are only a handful of choices and only limited options to really customize the character. On one hand this forces the player to really role-play to make their character's unique and vital but for some players this is a major detraction, especially those who prefer dice mechanics to player interaction. On the other hand however, it does serve to reinforce the world rather well. The culture in the setting is very good about pidgeon holeing its citizens so the limited class options make sense in that respect, still a few more options would be nice.
Overall, it is a well put together system and an interesting read that is more than worth the price of admission. It's a rules-light system with an engaging and interesting world. Download Novarium and enjoy.