I'm very satisfied with the choices and is not aware that there are any complain about it. As someone who played a lot of this type of game for YEARS, the flavors of choices offered in your game is exciting, and the plot is superb. There are a lot of IF that offer less choices than yours, especially in here.
I don't feel that the game is so linear as to warrants a disclaimer about it. Even your landing at the city offers several different outcome already! The disclaimer offers a disadvantage that you may want to consider; people might hesitate more before trying the game out as 'linear' often means that it's a 'moving storybook' rather than IF, and I heavily disagree on this definition for your story. I personally think that it's better to have them play and decide it on their own terms first.
But all in all honesty, this is your game and it's superb! Love your work, don't be discouraged, and wish you all the best and an abundance of luck in life!!