The metro was amazing and easy to understand and learn. I was in Paris for a week and mastered the routes by the second day. Granted, I found that walking around was more my thing but when I was tired, feet were hurting and stomach was rumbling, I was able to jump on the metro and get back to my hostel in no time. Also, I liked the little pink bunny rabbit stickers on the doors showing what would happen if you let the doors close on you. Not sure if those are still around