We upgraded to Economy Plus seats. Shortly before our flight United changed our seats because they switched the aircraft to one with a different seating arrangement. We ended up in one of the new Premium Economy sections (without an upgrade or cost increase). Premium Economy has more leg room and width than Economy Plus, and the seats themselves are more comfortable. (We flew back in Economy Plus and missed the comfort of Premium Economy.)
The flights themselves were fine, and the crew on both flights were excellent. They have to have the patience of a Saint to deal with the people who are trying to jamb large bags into the overhead bins and who do not follow the crews' boarding instructions.
I'd give United 5 stars for the flights, even the food was quite acceptable, but my rating is apparently supposed to be for the airline, not the flight, so I knocked it down a star to reflect how incredibly hard is has been to check on the status of a refund for an upgrade we did not receive. Forget about calling United. We understand that they are probably dealing with zillions of panicked people calling about the virus, but even the website is hard to use and buggy. (Venting: The other problem United has is one they share with the other main-line carriers. We were willing to pay to upgrade to Business Class, but our tickets were not eligible for a paid upgrade at any cost. However, we were able to request a Mileage Plus upgrade. Now, I'm no financial genius, but wouldn't it make more sense for the airline to take our money for the upgrade then to fool around with the miles stuff?)
Bottom line: United is a safe way to fly and has some really great people. For long flights like this one, we will always try to fly in Business or the new Premium Economy section. I'm too big for Economy seats!