The mod pack has quite a few mods (Mainly tech mods) but some people may branch to metallurgy or to the breeding of ore chickens or maybe to the aspect of RFtools for the mechanical aspect of it.
Most of these mods do take some time to get used to and so I will add a link to some guides for some of the mods like RFtools or Thaumcraft or Draconic Evolution.
Also this mod pack is to "hopefully" bring magic and tech together is a somewhat balanced pack for everyone.
The Wiki Links to the somewhat harder mods to learn are below:
RFtools - https://ftbwiki.org/RFTools
Thaumcraft - http://minecraft.gamepedia.com/Mods/Thaumcraft
Draconic Evolution- https://ftbwiki.org/Draconic_Evolution