The enterprise architecture development should be evaluated to assess
1. its scope, if it covers the whole enterprise or at least it plans to, starting with the parts specifically demanded. A reference (business) architecture (such as GODS) would be necessary to compare to.
2. the fitness for purpose of the artifacts, judged by stakeholders and if designed according to initial specification. A framework that establishes standards and principles (like FFLV) would be recommended.
3. how much progress has been registered in modelling the parts specified in scope.
Completion must be judged against the specification for that iteration and against the plan.
4. And most importantly, if the parts are integrated so that they form a whole that can be navigated from artifact to artifact and zoomed in/out to find out how processes work, who/what resources perform them, how a capability is implemented, the mapping of strategy to EA components... This demands a proper framework and metamodel (e.g. FFLV framework)
5. How much the EA outcomes are utilised in the enterprise (how many stakeholders and reasons of why not)
The communication and education process should also be checked for effectiveness or else the EA would be little utilized and as such would return little value to stakeholders.
Results of evaluation can be:
It does not cover the whole enterprise.
It only depicts the IT of those parts.
The degree of completion of many artifacts is low.
The parts are not integrated, that is linked so that the EA can be navigated for a purpose.
The EA has not been communicated so there is little awareness and as such usage.
A proper EA framework that establishes what are the parts of the enterprise, what artifacts are to be designed, how are they presented (what diagrams) and how are they integrated is essential since otherwise there is no objective way to assess the maturity and progress of the EA itself or compare the it with other developments. It should be a proper framework unlike many current ones that describe mostly the EA development process with all sorts of project management additions. Read FFLV-GODS and ask questions.