I agree with jacquest, I think the requirement of a B1 level for nationality is still too low.
I was looking at the link that Bev provided and I noticed the following:
"Le niveau requis est le niveau B1 du cadre européen commun de référence pour les langues. Il correspond au niveau d'un élève en fin de scolarité obligatoire apte à écouter, prendre part à une conversation et à s'exprimer oralement en continu."
Am I the only one that questions this? I would like to think that a native-French speaker would have a higher level than B1 at that age.
I took the DALF C1 a year ago and found it difficult. I wasn't a student at the time, I was working full-time and taking care of my husband after an operation. I looked at the official DALF exam book a few times and went in there and wung it (as a side note, anybody know the past tense of the verb to wing it as google is undecided?). I've spend the last few years in France speaking only in French and I only passed thanks to my high score on the speaking section. I arrived in France in 2007 with a B1 level.
I did the B2/C1 exam in Dutch a few years ago. At the time I sat that exam I had only been studying Dutch for the past 7 months, and I started from scratch. I did the exam following 7 months of intensive language study and preparation for the exam. I found the exam to be far more practical than the French one. I passed the exam with a score of 70% (the minimum required to pass).
I found the French exam to be "fluffy". It seemed to me that the article to be read in the written comprehension section was just saying the same things, laying out the main points in different ways, over and over again. You had to follow a protocol for the writing section and I felt I was just writing "fluff". I think that a big part of the French exam is following the rules and producing a certain style of written and oral expression. The Dutch exam was more practical in the sense that it only tested your Dutch language abilities. I am not a philosophical person, I am practical and to the point.
A friend who had done the DALF exam before told me to go in there and just talk, talk, talk during the oral expression section. Go in there confident and sound like you know what you're talking about. I went in there and turned the discussion into a political debate, regularly interrupting the examiners and contradicting their views while presenting valid arguments. This is exactly what years of French dinner dates spending hours debating around the table had taught me was the right thing to do. From an anglo-saxon perspective this would have been rude. I think the examiners enjoyed debating with me, haha. I aced the spoken section.
In conclusion, I think that the exam is easier for someone that is studying the language in a formal setting at the time they take the exam. My experience with the Dutch exam showed me that. The type of learner you are and the exam format are important as well - I just found the French exam too theoretical for my liking.
Other people's experiences are different. This is just my experience. I do think, however, that most people will agree with me when I say that the French language exams are not just about testing your language abilities, but about learning and using the French style of taking exams.