The presence of an official, normally-downloadable 64-bit Cocoa installer is by far the most urgent thing for this release, I'd say.
AFAIK the Carbon-based IDE simply doesn't work on the latest OSX release, and cannot be made to work.
Otherwise, for example, when someone inevitably posts the announcement on Reddit, the thread will just devolve into a bunch of people commenting about how Lazarus "isn't really as cross-platform as it claims" or similar sentiments, which is hardly good PR.