For me, "Cold Days" was somewhat of a departure from what I love about The Dresden Files. "Battle Ground" was way over the top for that departure. I still look forward to the rest of the series, but I do that looking with some trepidation.
Since Jim Butcher no longer reads this forum, it is unlikely that any of our thoughts posted here will reach him.
I loved Cold Days. I loved Skin Game too. The only books I had real problems with were Ghost Story, for reasons most can guess, then Peace Talks and Battle Grounds. It's hard to put into words, there was just a dissonance with the works that came before. Maybe it was because it went deeper into pure grimdark than it had before. I am not sure that was it either. In Changes, Harry was pretty stressed and didn't go in for much humor either.
I just got the feeling that Jim had painted himself into a corner and wasn't quite sure how to execute the escape.
That said, it was still a Dresden book and a mediocre Dresden book is better than most stuff. I am kind of hard up for stuff to read now. Jim's release schedule has slowed to a crawl and my other series just wrapped up, the Alex Verus books.