According to the Oxford English Dictionary, aspect has the Latin root aspectus, or "to look at". Having searched the OED for an adjective with the same root, there is the word aspectual with two meanings:
- Pertaining to aspects. Obs. rare
- Grammar. Of or pertaining to an aspect or aspects (see aspect n. 9b).
Note that the first meaning is now obsolete, and the second is only used to describe elements of grammar. So, we need a word which is still in common use. However, if you are using this to name an interface then I believe you can still use aspectual on the grounds that it maintains a clear link to aspect.
If, however, you are looking for a word which is still in common use, we must look at synonyms rather than true adjective forms. There are several senses of aspect, each with different synonyms.
One word which touches on a few common sense--a visible feature, and a part of something--is facet. To describe something which has aspects or facets, you can say it is faceted:
fig. Having a number of aspects, sides, or qualities; resembling an object which has been cut into facets. Freq. with preceding modifying word. Cf. multifaceted adj. 2.