I have had the QC35's for 9 months and don't regret it, they are super comfortable, sounds good, ANC is amazing. There is not really any sound leakage, if you are looking for great traveling headphones you can't go wrong with the QC35's. From using them daily when I do groceries, when I go to pay and slide off the headphones I sometimes almost get surprised by how noisy the store is.
The sound quality is not as good as my B&W P7's but pretty decent, on the other hand they are much more usable for daily use when you are not just sitting in from of the computer.