Just wanted to let two of the posters above know that CO is joining *A. They should correct their posts.
Now for AA disadvantages. The disadvantages of AA are:
1. No E+ seats--AA exit seats are NOT AS GOOD. And surely coach to NRT vs E+ is not worth comparing
2. Poor coverage of AA/OW Flights in many parts of the US/world
3. Few OW partners---hence less options for reward redemption
4. Older fleet
5. Higher prices now for routes I like---esp. Australia, Europe---right now I am trying to find flights to justify flying with them but I see UAL to/from Austral. fares and......
6. Use partners to cover too many routes hence not enough miles earned or upgrades redeemed.
7. Until july upgrading with miles is much more expensive than UAL
These are just some off the top of my head---I know there are more.