I've flown Delta nationally and internationally for many years. Overall, I've been happy with the airline, even though I've had some interesting experiences. The service is usually good, the food, too, and check-in and baggage usually are no problem. I have been able to redeem my miles for a domestic flight without any issues.

Occasionally, there have been delays, usually in Atlanta. Last December, a few days before Christmas, they hopelessly overbooked a plane (by over 40 people!), and it took an hour to finally figure out who could go and who couldn't; they actually had to get on the plane...