In my opinion the success is measured by:
Was the solution implemented?
Did it provide the expected results?
and finally, Is the solution flexible enough to withstand change?
I mention the last one because IT is built on top of change. Any IT Architect (of any vertical) must incorporate the change aspect on its solutions. Please do not reduce the support for change just to the upgrades and additions to the solution. The end-of-life, disposal and deployment of new solutions also counts as change.