Well, I broke down and watched it last night. Assorted musings follow...
Whole lot of liberties taken with the stories. The acting wasn't so bad, in that they did a good job of being party animals and emulating the behavior of Motley Crue. Machine Gun Kelly was surprisingly good as Tommy. The guy who played Nikki Sixx looked too young at the end of the film, like no time had passed at all throughout the course of the film. Iwan Rheon does not look like Mick Mars; he looks like Iwan Rheon in a bad wig, his body type and facial structure is not similar to Mick's. I enjoyed some of his lines, though. He played the part well.
The guy playing Vince Neil did a good job making me hate him. Back to the liberties taken with the stories - yeah, I did not really like the portrayal of Vince's car crash. And why did they even bother including the situation with his daughter if they weren't even going to address it at the end of the film?
The pacing was the biggest problem with the film besides some of the loose storytelling. If this was like a 10 episode series, they would have so much time to give character growth and development (insofar as there is any of that with Motley Crue), amp up the tension and drama behind dope addicts utterly destroying themselves and everything around them, and build up the power behind events like Vince crashing the car, Nikki overdosing, Corabi taking over on vocals, and MC's fall from popularity. Instead it's just bam, bam, bam, here's another scene with another crazy event, no time to breathe or really elaborate on much. I wasn't expecting the Ozzy scene, though, which was funny in a gross and horrifying way.
The best parts of the film were simply watching the guys be party animals and rule the stage. They did a great job playing their parts on stage and looking like real, ass-kicking rock stars, and the soundtrack full of Crue songs was perfect. I don't recall hearing Too Young To Fall In Love though which I was SO excited to hear at some point.