Hmm, sort of? I can't really generalize from my own (first year, before joining a lab full-time) PhD courses, but I found them challenging in a way that differ

Hmm, sort of? I can't really generalize from my own (first year, before joining a lab full-time) PhD courses, but I found them challenging in a way that differed from undergrad: more expectation that you'd be able to figure out the solutions to the hard problems by learning entire new fields on the fly.