I don't actually go to Five Guys in America, admittedly, because it's a bit on the pricey side and…read morenot much in the way of vegetarian options. I will say, however, that you're paying for quality, at least.
What I love most about the restaurant's existence in Frankfurt is the good old US standard free soft drink refills that are so hard to find elsewhere in Germany/Europe. As someone who drinks a ton while dining out (usually water, not soda), it's a relief to know there's at least one place I can go where I don't have to decide between stressing my wallet or going thirsty.
I tried a mango milkshake, and it was unexpectedly delightful. Also split an order of fries, which was HUGE and well-seasoned.
A little piece of Americana right in the heart of Frankfurt.