This is book 14, so no introduction to the plot or summary of the series so far will either make sense to new readers or be interesting to series regulars. So, instead, it is worth asking, is Cold Days worth reading if you are already a Dresden fan? And, perhaps more importantly, does it give you hope for the continued adventures of Dresden in the future? The answers are both "hell, yes!"
Remember, we are 14 books into a series, one in which hundreds of characters have been introduced, where each book reveals bigger secrets than the last about the universe, and where every potential proverbial shark has been jumped, including the resurrection of the main character. And yet Butcher somehow, against all reason and expectation, keeps writing books that feel as if there is an overarching plot that makes sense, with real character progression, internal consistency, and a vibrant but changing world.
It is worth noting this achievement, since, to my knowledge, no fantasy or science fiction series of this length has ever pulled off a series of such consistent highs, and on a nearly yearly basis! Robert Jordan and George R. R. Martin lost steam along the way, Bujold makes each story fairly self-contained, Pratchett switches characters, and most other epic series feel a bit like the TV shows Lost or Twin Peaks - spinning out of the creators control with needless complication and wandering attention. Not the Dresden files! The action is still exciting, the humor still solid, and the characters still engaging. And, as per usual, the stakes get ever higher, while still leaving room for both mystery and future books.
The short version: the book is excellent, and the series an achievement that has managed to transcend its fantasy-noir roots. The only reason not to get it is if you haven't read the first 13.