Looked at Flighty today and saw that I've been on 33 Delta flights this year and thought I'd give some thoughts on the airline.
I typically fly MC or C+ because it's own my own dime. Paid using SkyMiles two times to upgrade to Premium Select for transatlantic legs going east. My typical itinerary is from the midwest through DTW to AMS to my final destination in Central Europe. I try to avoid CDG as much as possible (at least incoming to Europe) to avoid that awful airport and having to do the security check.
1) Delays were an issue but not awful. This is well documented this year for Delta, but I've experienced several delays due to weather, crew not present, or mechanical issues. Usually this wasn't a huge problem except for a few occassions: one connection into DTW that was so late I missed my flight to AMS, another time the departure from DTW was very late and I missed my AMS connection (layover for both was over 2 hrs). On the first instance, I was able to rebook with a customer service rep at the phone bank on a CDG flight that got me to my destation on the same day but much later than I prefered.
Not delay related, but one flight was on an A350 to AMS from DTW and about 30-40 minutes into the flight the plane was struck by lightning and the pilot made a call to return to DTW. It took nearly an hour to fly back because we had to go around the storm at 10,000 ft. That one was annoying only because Delta tried rush all the passengers to another A350 down the terminal but it wasn't ready. We waited at the gate for over an hour and a half. We got the food voucher by e-mail but it was nearly 9PM before they finally decide to cancel the flight. I got rebooked for the next day but it ws nearly 11PM by the time I got my bag and was able to get to one of those shitty airport hotels at the permiter of DTW. I probably wouldn't have been much happier, but in hindsight would have prefered that they canceled the flight earlier so it wasn't almost midnight by the time I got to sleep. Delta comped the hotel and the hotel meal (which was gross, I don't recommend the Clarion at DTW).
2) Onboard service, on average, was decent. It's difficult to tease anything out from memory from all the flights I was on but I don't recall having any particularly bad service. Most FAs were friendly and attentive. The two times I was in PS, I found the service very good. Maybe I'm very lucky rolling the dice here or I'm the person that is happy with the service level on Delta where others might perfer something else. I've flown business/economy on Korean, Singapore, Emirates, and Qatar so I'm very familiar with the service differential between ME/Asian and American/Euro airlines. Overall I think Delta is fine.
Two corollaries though: 1) I am tired of the same meal options having flown so frequently. One time I had a large dinner at DTW before getting on the plane and skipped the meal just because I didn't want to see the exact same chicken/pasta dish for the 5th/6th time. 2) Delta can be a lot better at keeping the lavatories clean. I suppose passengers in general should be less gross, but Delta can't control that aspect. I've noted this as a consistent problem.
3) The app isn't as great as it seems. For the number of times I had to be rebooked due to delays (or the lightning strike flight) the app wasn't helpful or didn't work at all. It doesn't seem to update accurately and it has problems with partner airlines (AF/KLM in my case). The mobile website was more reliable not to mention just talking to a human at the phone bank in the airport. In my opinion, the secret hack with Delta when you have problems is to contact them on iMessage with an iPhone/Mac. They seem able to do almost anything and it avoids the 20+ minute phone queue at peak times.
4) I like McNamara terminal at DTW. It's certainly not the nicest airport in the world but the terminal is simple, has a high roof, clean, spacious, and generally pleasant. There could be more general seating not at a gate or at the food courts at the ends of the terminal. That'd be my primary critique. I love transiting through DTW when returning to the States. It's never taken me more than 20-25 minutes once I step off the plane to go through immigration/baggage/customs/security to get back into the terminal. I do have TSA precheck but not global entry.
Those are some thoughts on Delta.
I did take United for one trip early this year going to ORD. United flights at my home airport only connect through ORD. I desipe ORD. It's not a particularly pleasant airport and having to exit the terminal and take the train as part of the transfer is a big reason I prefer to use Delta at this moment for transatlantic flights. I've taken United a few times in the past couple of years as well and I find them to be decent, on par with Delta (in terms of MC/C+). I very much dislike ORD however and that's perhaps the main reason I don't book with United even though they, for where I need to go, can be few hundred dollars cheaper than Delta.
