I think this can be pretty succinct:
The good (to often great)
When American tries to be the more premium airline it once was and compete. Flagship lounges, international business, ability to SWU upgrade on any fare, three-class transcons to NY, ice cream sundaes, OW benefits including F lounges, offering EXP/CKs food if they're stuck in the back in MCE. AA can and is a very very good airline TPAC and until new Polaris and upgraded BA club suites might have been the best NY-LHR for several years running
The bad
American domestic in Y - cramped pitch, more seats, no TVs, reduced offering for snacks (UA does a full hot snack service for charge that blows AA sandwiches out of the water)
The ugly
The ten thousand cuts that have hit elite passenger and employee morale the past few years because there is a management team and CEO for no vision as to whether AA wants to be the good or the bad, the premium airline or the LCC. Everything else fits here (poor IRROPS handling even for elites, reduced SWUs, etc)