if you know the von erich story, you know it's tragic. this is not a happy movie. my partner didn't know anything about the von erichs so, being the sensitive and empathetic soul that she is, she cried a lot. i think a lot of that can be attributed to iron claw also being the strongest depiction of a loving, supportive family, warts and all, that i've seen in a movie in a long time, which gives it a strange and bittersweet wholesomeness amongst all the grief. a couple scenes eschew reality quite a bit, some of the wrestling is presented as though there are real stakes in winning and losing despite the movie not shying away from acknowledging how wrestling is presented, and there are absolute liberties taken with the von erich history to present a more concise story, but they all work well for the the film- this is not bohemian rhapsody in that regard.
it is the performances that really carry the movie. i don't think there was anyone in the ensemble that didn't pull their weight here and bring their character humanity - every von erich struggles with something and the actors do well to demonstrate that. for example, fritz's application of love is misguided, abusive, and selfish, yet you do not doubt he loves his sons and family in the true sense of the word- he is very clearly happiest when he is surrounded by his brood. the movie shows that love for each other is what keeps the von erich family grounded - there are several moments depicted where one von erich is upset or struggling with something, and a supportive touch or words from another snaps them out ouf it, even if briefly.
the movie looks very good on the big screen, but it's probably not one you *have* to see at the theater given it is more of a straightforward family drama. i would encourage it, though, if you've got the time and interest in seeing it.