Generally speaking, I'm not a big fan of Agile Development for two reasons.
1. All the hype.
2. A lot of contradictory information and advice, sometimes from the same person. One time you hear that you have to adopt all the steps of a given methodology. Another time you hear that you can't be brain dead about adopting the steps, but need to pick and choose what works for you. A big selling point of Agile is little documentation, given that as a rule developers hate writing documentation. But then this gets taken to its illogical conclusion and many of the Agile work I've seen has zero design and planning. People just start coding and think the design will magically assert itself at some point. In fact, for a trade that generally prides itself on being logical, there is a lot, in practice, that I see illogical about adoption of Agile methodologies.
That being said, I agree with the position of most items on the Agile Manifesto. It's just in practice I haven't seen it work too well often. Even the reported successes are usually qualified and, depending on the stakeholder you ask, the success really isn't a success.
To that end, I think this latest entry on Artima is a good read and crystallizes a few of the issues that lead to this state of things. http://www.artima.com/weblogs/viewpost.jsp?thread=246513