He seems to really 'get' Star Wars-he's co-written four (ESB, ROTJ, TFA and SOLO) of the now ten films, and seems to work really well with the more humorous aspects of the films (At times, it felt like TLJ sort of was trying too much to go for the more slapstick humor of the prequels, especially during the Canto Bight sequence). Apparently he didn't work on TLJ because he was busy with Solo, and wanted Rian Johnson to do his "own weird thing".
Not sure what episode 9's script status is, although I think Abrams was more or less working on it mostly by himself although with probably at least some of the foundation from when Colin Tremorrow was involved..