Main features to be aware of:
The gameplay is centered around finding and beating multiple new bosses, spanning multiple dimensions.
multiple modes of advancment refers to the few magic based mods added into the pack insuring unique ways to deal damage and farm for rescources. this pack includes Mekanism, giving you a technical way to farm rescources and aquire new abilities. Using Mekanism to automate mining it would be vary easy to mass produce bullets from a gun mod thats included if you want to emphasize a ranged playstyle in your playthrough.
If you like ranged playstyles but dont want to get involved in the complexities of Mekanism there are other mods that give options in the terms of guns. such as Alex's mobs which brings a blood gun
Nearly every mob in this pack has a chance to drop unique and special items, many mobs are also tameable which gives a "beast master" sort of playstyle.
chests have a high chance to contain new items as well spanning the mutliple dungeon mods in this pack, with varing loot in dungeons it is possible to obtain high tier loot without even stepping into a cave to mine rescources.
With server based addons this pack is intended to be played multiplayer and give everyone involved a unique playstyle if they so choose.