In any long-running monthly comic series, there are going to be plenty of good ideas and plenty of bad ideas.
The addition of Matt Murdock's "twin brother," Mike Murdock, to the Daredevil series was a bad idea. Back in issue #25, blind attorney Matt Murdock's secret identity got blown, so to mislead his partner, Foggy Nelson, and his beautiful secretary, Karen Page, Matt showed up with wraparound shades, a loud jacket, and a collection of funky hats, strutted around without a cane (he can do that, you know, he's Daredevil), and claimed to be a long-lost twin brother named "Mike." With this not-especially-clever trickery, Matt convinced both Foggy and Karen that Mike was Daredevil.
I suppose there might not be any "bad ideas," just so-so ideas executed poorly, but whatever the case, "Mike" Murdock was a really stupid character who spouted all manner of nonsense jive talk and hep-cat lingo, and added little to the story.
When the character finally "died" in issue #41, I breathed a sigh of relief. Daredevil's rogues' gallery is still middling (e.g., Stilt-Man, the Unholy Three, the Jester), and Stan Lee's prose is hard to handle in large doses, but these early Daredevil stories are still a lot of fun.
The best thing, for me, is Gene Colan's art, which is still just gobsmackingly cool. His figure work is brilliant, and Daredevil's body has a great sense of long, lean movement in the action scenes. Colan also did a lot of constructions and layouts that were way ahead of their time. This volume is worth reading for the art alone.