I am a big fan of agile development and used XP on a very successful project a few years ago. I loved everything about it, the iterative development approach, writing code around a test, pair programming, having a customer on site to run things by. It was a highly productive work environment and I never felt like I was under pressure. However the last few places I have worked use/used Scrum. I know it's the poster child for agile development these days but I'm not 100% convinced it is agile.