Those are missing features that did not make it into "2.0 final".

The best solution would be to implement those:
* `$constraints` should [work the same](http://framework.zend.com/manual/2.0/en/modules/zend.mvc.routing.html#zend-mvc-router-http-segment) as in [http routes](https://github.com/zendframework/zf2/blob/master/library/Zend/Mvc/Router/Http/Segment.php#L213) - copy-paste would most likely work fine + tests.
* `$defaults` would need to be implemented in the "matcher" same as in the route object.
* `$aliases` are self-explanatory.
* `$filters` is just an array of  `Zend\Filter\FilterInterface` instance (i.e. filter chain)
* `$validators` is an array of instances of `Zend\Validator\ValidatorInterface`.

Filters go through captured param values, then validators are invoked. If any validator fails, this equals to route mismatch (`return false`).

This way we'd have both the BC and all features covered.