“Hassle” is relative. It’s just as easy or easier than the 220 countries outside the EU. Ya know, the ones with north of 20x the population of the EU.
The only immigration system I am aware of that's more hostile is US. Obviously there are many countries I know nothing about
More important however might be the interaction with locals. And from what I witnessed, Americans (well, Californians at least) are much more welcoming than Germans.