The full list of resolved issues in 1.8.4 is available here.
AspectJ has had type category type patterns since version 1.6.9, see the README. This enabled pointcuts to include is(..) clauses to specify which kinds of type they were or were not interested in matching, e.g. !within(* && is(InnerType)) means not within innertypes. In 1.8.4 it is now possible to recognize (for inclusion or exclusion) final types with is(FinalType).
This is the key fix in this release. Some products based on AspectJ were using the thisAspectInstance feature (see README 1.6.12 for more info on the feature). Unfortunately if specifying -1.8 compliance and using the feature an error would be reported at compile time of the aspect. This is now fixed.