The Skaven is personally one of my favourite new factions due to how differently the play, refreshing to play swarm tactics every once in a while.
I think a lot of people will be disappointed that this leader is from a lesser Skaven clan, but this is free DLC after all. The Free-LC roadmap points to an Elves DLC lord next and then a Lizardmen lord. Lots of people were expecting clan Skyre or Clan Moulder for the Skaven.
A Skaven clan with an affinity for Frozen terrain will also allow for some more action in the tundrous regions of the map, which is good for campaign variety.