As someone who has played through nearly all of the dlcs for Rome 2, I can tell you this one is the most unique.
The Nomadic Tribes culture pack allows you to play as the Royal Scythians, whose starting position is modern day ukraine,the Roxolani, and the Massagetae, whose starting positions are respectively northwest and southwest Kazakshtan. The distance of these provinces from the heart of Europe really makes this campaign a struggle, and for the most part your first 1/4 of the campaign will be spent fighting other nomads with similar rosters, amplifying the challenge. There are new building trees for nomads, and the culture certainly distinguishes itself from any other barbarians. The new units the nomads are given diffrentiate playstyles, the Massagetae, for example, are heavily armored and therefore can hold their own against both powerful cavalry units and swarming spear units. The Roxolani have units that promote fast charges that cripple an enemy, but should not stay in the fray too long. And lastly, the Scythians possess the best skirmisher cav. in the game, allowing them to devastate both melee and cav. units.
I do have some problems with this dlc, one of which is that the nomads appear identical to the barbarians, with a germanic look to them, when they were in fact of Indo-Iranian blood. This just feels like laziness from CA and a lack of understanding of ethnicity. Another problem I have is that on the campaign map, the Nomads don't feel particularly distinguished from any other factions and capture and occupy settlements with the rest of them. This just bugs me completely, because I had assumed the nomads would possess a lifestyle similar to the migrators in TW Atilla, never really settling in one place until they have the wherewithal to do so. Lastly, this culture pack should not be paid dlc, given the lack of any playable nomads in the basegame, and their pisspoor rosters before this dlc.
However, I would encourage anyone who feels like the base game is missing diversity to purchase this dlc, as the Nomads truly feel unique and different from more "landed" factions.
-Difficult Start Pos.
-New Buildings and Tech Trees
-Factions possess different playstyles
-Factions feel ethnically identical to barbarians
-Lack of "Migratory" lifestyle