IEP Conundrum -- What is Success?

Over the weekend I spoke with a friend about our experiences teaching special education. Although in different settings, we did have a surprising number of strategies in common. But one part of the discussion that brought up differences was a question about the meaning of IEP achievement. What makes a student's IEP successful to you? For me, the document itself came to mind. Are objectives clear and measurable? Did I take into consideration special services? What about monitoring and adjustment; involving other educators; incorporating a student's present level of performance. For my friend, they thought of IEP success solely in terms of student achievement / reaching goals. The structure or document mattered less to them. What do you think?