The follow up volumes are awesome too. Duane Swierczynski and Travel Foreman did a great job continuing the series after Fraction left. I strongly recommend picking those two volumes up as well, if you haven’t already done so.
Funnily enough, Fraction’s Defenders run also picks up from the end of Immortal Iron Fist too. That’s not so great though, unless you like Fraction’s crazier, more out there stories.