Oh, for most people quantum mechanics is harder without a doubt. Basically, the reason that classical mechanics makes sense to most people is because it deals with the macroscopic objects we interact with on a daily basis. You throw a thing, it hits another thing, the second thing moves. read more
Quantum mechanics is vastly harder to grasp and is famously unintuitive, at least to begin with. As with any skill, training helps, and professionals generally don't find it confusing any more. So, don't give up on QM. When you get down to it, that is how the world works. Classical mechanics is a simplified abstraction. read more
He was an expert in dynamic systems and just couldn’t accept people wanted to “understand quantum mechanics without understanding classical mechanics” – which according to him, was way much harder. read more
Honestly, beginner's quantum is pretty easy. I'd say Griffiths level quantum is easier than Griffiths level E&M though you might have some difficulty if you haven't had a good classical mechanics education. I'd recommend just picking up the griffiths QM book (it's standard) and reading through it. read more