What is your experience or your opinion of the Scrum agile software development methodology?

From

http://en.wikipedia.org/wiki/Scrum_(development)

Scrum is an iterative, incremental methodology for project management often seen in agile software development. Although Scrum was intended for management of software development projects, it can be used to run software maintenance teams, or as a general project/program management approach.

Scrum is a process skeleton that contains sets of practices and predefined roles. The main roles in Scrum are:

1. the “ScrumMaster”, who maintains the processes (typically in lieu of a project manager)
2. the “Product Owner”, who represents the stakeholders and the business
3. the “Team”, a cross-functional group of about 7 people who do the actual analysis, design, implementation, testing, etc.

During each “sprint”, typically a two to four week period (with the length being decided by the team), the team creates a potentially shippable product increment (for example, working and tested software). The set of features that go into a sprint come from the product “backlog”, which is a prioritized set of high level requirements of work to be done. Which backlog items go into the sprint is determined during the sprint planning meeting.