As is the case with any of the standards, benefits of registration are varied and impacted by the condition your system is in now, what you want out of the process and how much you put into it. An organization does not "get" ISO anything, except when purchasing a copy of the standard. ISO standards are frameworks for business operations that are intended to guide users in establishing structure and controls.
Implementing an Information Security Management System is what you "get" from ISO 27000. So the questions becomes, "Would my IT company benefit from having better controls over information?" Every day we read about hacks occurring. If you do some form of risk analysis, what does it tell you?
Only YOU can decide the answer to this question. If you then seek certification - as Jennifer describes - such certification of your ISMS may help to bring confidence in your customers and allow you to sleep better at night, because there's less risk that your organization was the weak point.