Speed to market

Agile lets you get your concept to your users as quickly as possible. During every sprint an agile project delivers something of value. At any point, you may determine you want to launch what has been delivered and start building a user base or testing your hypothesis.

Flexible

Agile is based on accommodating change. Software projects consistently change. As a product comes to life or the market expands, you should be able to react and update the product accordingly. Agile also realizes that great ideas are bound to come mid-project and being locked into a scope doesn’t let you take advantage of these realizations.

Risk management

Incremental releases means that the product can be used early in the process by stakeholders and users. This lets you identify issues and feature deficits early in the process. Being adaptable to change means it isn’t a problem to change the scope midway through the project, something that would be impossible in a waterfall style project.

Cost control

Unlike a fixed budget project, agile is flexible with regard to scope. More often than not, our clients realize features they originally requested are no longer necessary. This allows them to launch sooner and pay less. Agile isn’t about paying a lot with uncertainty, it’s about paying for only what you need. Need to stick within a budget? No problem! We can rearrange the product backlog so that critical new features are implemented at the expense of less important features, not your budget.

Quality

Agile integrates testing throughout the process. Consistently delivering tested software means higher overall quality and less time spent on qualifying the full application.

Right product

Incremental releases let you test your product early and often. Even if you don’t release it to the public, it’s much easier to locate flaws and things that can be improved when you have an actual product to play with vs a series of designs.

Transparency

Agile lets you see, feel and use a project consistently throughout the project. You don’t see things in compartmentalized silos; you see how things work together.

Source: http://agilehandbook.com/agile-handbook.pdf