Every once in a while, it becomes super popular in various groups of occultists to argue about Aleister Crowley. In the OTO and A.'.A.'. groups I interact with, the debates usually boil down to ways people make it ok to be a Thelemite even though he was a bastard who got some things terribly wrong overall.
Outside his cultus, people argue about how important he is to modern occultism. Jake Stratton-Kent and I were talking about it the other day on FaceBook. He doesn't think Crowley was the greatest magician ever, and I agree. Not the greatest ever, but certainly the most influential of the last 1500-2000 years, within the modern western mystery tradition.
I personally believe that less than 1% of English-speaking modern occultists are untouched by Crowley. Every system of magic in the English-speaking West finds its way back to To Mega Therion at some point. Even systems that think Crowley is shit still go to pains to differentiate themselves, and thereby define themselves using Crowley's teachings and methodologies. So even when people hate Crowley, he's still influencing their practice and their minds.
But that said...
Who gives a fuck? There's nothing Crowley wrote or taught or learned or changed or presented that is necessary to accomplish "the Great Work." People did it for years before he came along, and people will keep doing it long after he's gone the way of Buddha, Moses, Christ, and Mohammad.
In the mean time, if you read his stuff and it resonates with you, enjoy it. If it doesn't, do something else. There's nothing any Order he created, changed, influenced or destroyed on the planet that has anything in its teachings that you must receive from that group to accomplish the Great Work. The Golden Dawn, OTO, and A.'.A.'. are not the only way to the Philosopher's Stone, and for a lot of people, they will hinder your progress more than help.
So many times when I see people bashing Crowley, it's to make themselves look smarter or more important in comparison. I can count on one hand the number of magicians I've met who criticize Crowley who have actually read his works and understood the intent of his practices. Jake Stratton-Kent and Jason Miller pop immediately to mind. Most other critics make their statements based on ignorance, lack of comprehension, and lack of study.
Actually, I'm being super generous. Most people talking smack about Crowley base their opinions on what they heard about him rather than what they know about his life, times, and work. Because they're lazy and would rather feel good about themselves for thinking poorly of an icon of magick than actually do anything necessary to begin to become one themselves.
Folks, the Great Work is not a competition. You are not a better magician because you can point out what other magicians have done wrong. You are a good magician when you accomplish the Great Work, whatever that means to you.
Crowley can be useful in that pursuit for some people some of the time in accomplishing some things. There can be value in understanding what Crowley got wrong, but if that's all you see when you look at his Work, you're missing out on everything he got right...
And I'd suggest your time would be better spent pursuing something else.