The appeal of Dresden is that he was mostly a normal guy (with some powers), that dips his toes into a supernatural world that’s a lot bigger than him and could crush him easily, but with a lot of luck and a little cleverness he manages to live through it. He’s a wizard, but doesn’t really fit into the wizarding world and really relates to normal people better (though he doesn’t really fit in there either).
That’s a fun story, but there’s only so much you can do with it before it gets hokey and repetitive. Dresden hit the nerve of the nerd community, got Butcher some popularity, and became a cash cow he could milk. Butcher’s writing improved over time (watching his skills improve notably from book to book in the early years was great), but it’s hard to avoid the traps that come with a long episodic story like the Dresden books became.
There are great high points, but a continuous string of “woe is me, I hurt everyone around me”, emo mopefests wears thin after a while. Continuously escalating power In your main character is another trap (let’s just call it “Anita Blake syndrome“), which leads to continuously escalating antagonist powers, which eventually becomes ridiculous.
Butcher has some tremendous moments, but he also has his weak streaks too. He created some really interesting sub-characters, but doesn’t always know what to do with them, and he’s done about all he can do with his main character without getting absurd. I fear that (maybe) Dresden has become Butcher’s avatar for his own midlife doldrums.
My opinion (worth what you paid for it) is that Dresden should have been put out to pasture about 6-8 books ago. Some spinoff books about other characters (Molly Carpenter’s short dive off the cliffs of emo doesn’t count) would have been cool. Unfortunately (with the exception of Bitters), it looks like every time those interesting characters try to go off and do something interesting on their own, they crash and burn because they’ve all become physically, emotionally, and from a narrative POV, utterly dependent on Dresden (the biggest trap Butcher has fallen into).
Good urban fantasy has to start with a great idea with unique spin. Butcher nailed it. It needs an interesting worldscape and characters. Again, Butcher did a great job. I think he made some mistakes and fell into a few pits along the way, but it’s been a great series. I just think it’s time to let Harry fade away.