I finished the last episode tonight. I enjoyed it well enough- I think I would put it below Season 1 of Daredevil, but above Luke Cage. The interplay between Cage and Jones was the high point for me- I like and believe their chemistry, and Ritter and Colter are probably the most consistently charismatic leads in Netflix's Marvel universe.
I'll echo what everyone else is saying, though, that Iron Fist is a problem. Somewhat to their credit, I think the showrunners are starting to recognize that- lines like "You are the dumbest Iron Fist ever[/i]" and, "Yeah, and he'll say that to anyone who'll listen [that he's 'the Immortal Iron Fist']" read like audience surrogacy, and relatively few of the other characters seem to have much patience for his schtick.
But he really needs to develop more character than naivete, stubbornness, and a tendency to rush into every situation head-first. The wall-punching incident in the penultimate episode is just cringe-worthy. Netflix's Marvel shows are united by eagerness to give the lead characters hard knocks as much as the presence of Rosario Dawson; in a world as gritty as they seem to want theirs to be, one wouldn't expect a character as short on finesse and as narrow in capabilities as Danny Rand to survive for very long.
Oh, and Misty? Good grief, am I tired of Misty. She's supposed to be an amazing detective, and she all but inevitably shows up to be wrong and to persecute the wrong people. Even by the end where she's sort of working for the right side, it comes as an utterly unconvincing result of Claire's "You know Luke Cage is a good guy" speech, because she's had plenty of occasions of seeing that Cage and others were good guys and it hasn't stopped her from arresting them. She's less a character than a road block, an irritant. She shows up and momentum towards more interesting happenings comes to a screeching halt.
I'm unsurprised, though a tad disappointed, that Murdock survived. Better than even odds we haven't seen the last of Elektra or Gao, either- I hope, but don't expect, that the explanation is more than some vague hand-waving.
Still, it entertained me. It could have been tighter, but it didn't make me groan most of the time, and I was at least slightly curious how things were going to turn out.
I'm not exactly enthralled by the idea of following The Punisher around for a season, but on the basis of Defenders, I'm at least willing to consider that they're back on the upswing.