Interesting perspective. I was just so happy that the first one was better than Iron Fist that it may have biased me towards it. It does take a while but it does come together into one story.
I guess it suffers from the same thing all origin stories do... it takes some time to get into the full swing. This is unique because it is the origin of a team.
If you liked the first 4, you should give it another try. It will get there.