I work for a very large video game company, and agile works for us. My team has a twin-team, one that uses 3 week iterations while ours has adapted to 1 week iterations and it works great. We release often and early thanks to various automated processes we employ, making life easier for everyone. Managers stay happy since they can actually see progress and measure team velocity which results in an actual accurate sprint/accurate planning. Planning for our iterations doesn't take that long also with smaller iteration cycles. I am happy with it.