Go and try it - the food is delicious, you won't be disappointed.
That said - it's Banh Mi. Go to any mom and pop Banh Mi shop in the city and the sandwich is $2-3 tax included. Here it will set you back $8-10. My 4 stars is for the pricing of what in Vietnam is a humbling and cost friendly experience of cross cultural fusion. At BMB it's just a little too pretentious for my taste. Everything is delicious, but you're paying for an environ designed to cater to the Western consumer. I suppose you cannot blame them for their business sense, but it just rings off inauthentic.
Amazing kimchi fries, even if it's a day's worth of calories in a bowl- you gotta get those. Don't get it as a side on your own unless you are morbidly obese or like to throw away food.