ITIL provides great benefit to numerous organizations around the globe, but a word of advice - BE PRAGMATIC !
ITIL needs to work for your organization and not the other way round.
In some situations you may need to adapt ITIL or other elements of ITIL to fit to your organization's requirements. That is not to say that over time you may bring the organization into line with ITIL.
We have worked with several organizations that become 'hung-up' on ITIL and what is stated in the ITIL publications as they attempt to implement it line by line.
We also find employing the services of seasoned professionals, who have implemented ITIL in various organizations before, can both save time and money as well transitioning knowledge to existing employees thus improving their skills and knowledge and reducing the dependency on third party consultancies.