There are some more subtle changes.

Elite availability is now dependent on the person. If a plat makes a reservation for a friend then award availability is for the general member level. This used to be at the plat level and one could sometimes even reserve premium seating.

Loss of the Worldperks VISA and 2k supersize bonus.

Endless schedule changes with loss of seat assignments.

TATL saver award going from 50k to 60k.

18 month expiration of miles.

Huge increase in TATL B fares.

Partner award fee $25.

Confusion over SDC fees.

DL.com does not recognize NW status and does not allow selection of preferred seats.

Lots of things we've gotten used to do on NW.com are now gone or will be gone soon. Check flight/booking history, list e-certs, show promotion enrollment status etc.

Possibly the 1k upgrade guarantee.

Some of these would probaby have changed over time anyway but it has been a bumpy ride, especially earlier this year when all the changes were coming out (on FT, not in a DL/NW email). But the list goes on and there are almost weekly additions, mostly devaluations of the program.