As someone below also stated, his handwriting is legible, in a beautiful I would love to have that too kind of way. He always came to class prepared with numerous examples. If anyone ever needed help, he would assist them in office hours, going over any issues and ensuring complete understanding of the concepts. Awesome French accent - some people complained. Honestly it wasn't even that bad. Overall: nice guy, cool accent, knowledgeable, and very helpful. Would recommend.
If you are generally good at calculus, take this class. Gilles isn't a very good teacher. He has an AWESOME french accent which was fun to hear in lecture, but he wasn't very good at explaining things. Towards the end of the quarter is when it gets bad, because we start learning multivariable calculus which is unlike anything you've seen in high school calculus. As long as you're good at reading from the book and doing the problems, you'll be fine. Reading through the book and doing practice problems is how I survived the quarter. But if you rely on the teacher to actually teach you, you won't be fine. Test wise, his midterms were RIDICULOUSLY EASY!!! I got high A's on both, and I'm not THAT great at math. I did study, but not a TON, which is why I was so surprised. I studied a lot for the final just to be safe, thinking "the final will be just as easy as the midterms, I'll get a solid A no problem in this class." But I was wrong. :( His final was really hard. I was totally in shock, because I was expecting something at the level of his midterms. Everyone else in the class was groaning about how hard it was after too, so there will probably be a nice curve. Also, he says 56% of his students get A's and B's which is pretty good. OVERALL POINT: If you are good at teaching yourself and if you are good at integration/formulas/the like, this class isn't too bad. If you rely on the teacher to spoon feed you, you should look elsewhere.
Let me start by saying that his accent is awesome. Unfortunately, that's about the best thing I can say about him. Because of the accent, it took me to realize that he's a sub par lecturer who just copies his notes on the board without ever taking time to explain. If you want to write down everything he puts on the board you will be writing nearly nonstop for the entire fifty minute lecture. Midterms aren't too bad, but the final in 32b wasn't cumulative which was really disappointing since everything difficult in the class is covered in the last three weeks. If you have no other options, my advice is to take him and never attend his lectures, you will get nothing from them.