Summer Knight used to be my favorite early Dresden Files book. I think it’s useful to distinguish ‘early’ and ‘later’ Dresden books, because at one point they stop being great fun and become pure awesome. Summer Knight is not where it happens, but it is a very solid installment.
Taken together, Summer Knight and Death Masks are good examples of different story arcs in the series. There is the fairies story arc (Summer Knight), and there’s the knights/demons arc (Death Masks). There is obviously also one for vampires (Grave Peril etc). My personal preference is for knights/demons and fairie courts. I’m less enthused about vampires, but I do like the fact that none of Butcher’s vampires sparkle (though the ones in the White Court acquire a sheen when they are about to feed).
I finished Summer Knight and moved on right away to Death Masks only to realize that perhaps Death Masks is now my favorite early Dresden. It might be Shiro, or guys with swords in general. It might be that I’m more of a sucker for a ‘let’s find a priceless relic’ detective story than I used to be.
A note on the covers. Someone I know pointed out (correctly) that while Harry is pictured wearing a hat on all the covers, he never actually wears one in the books. My take is that the covers are designed to be very noir-ish, hence the addition of a hat. It’s supposed to make your detective look sharp and, for all we know, adds +3 to intelligence. To be honest, Harry is hardly ever a sharp dresser in the books (and, as my friend pointed out, also has an unfortunate predilection for sweatpants). It doesn’t really matter, to be honest. Hats are cool (sweatpants, less so).