The mod doesn't add much content yet because it's in Beta
In the new version of the mod, the world's lower limit is now -128 blocks. Ores have become less frequent, but the quantity within a single deposit has increased. In caves at the new depths, you may encounter familiar biomes as well as tougher mobs; the deeper you go, the stronger the hostile mobs become. A mod that improves certain aspects of chemistry, much of it based on real-life chemistry.
Some ingots can't be obtained simply by smelting them in a furnace; chemical reactions are required. Update 0.0.4 added a workbench where you can upgrade your equipment (currently, only steel and titanium armor can be upgraded, and only with tungsten).