My seat: 35D, on an aisle.
Fellow passengers: The couple next to me cuddled up together for much of the flight, resulting in a bit more arm room for me. Some of the passengers on the plane seemed strangely unable to sit down before take-off and the desire to carry on as much as possible to avoid luggage charges was evident.
How full: "We are looking for travellers who'd consider taking a different flight in exchange for a travel voucher" kind of full.
Entertainment: More than expected. About 40 movies (standard airline movie stuff), some interesting TV shows and music. Headphones provided. There are back-of-seat screens, plus Wi-Fi available, and entertainment available through the app.
The service: Efficient, friendly, standard.
Food and drink: A free 14g (that's little) bag of pretzel twists. A good variety of snacks and light meals to purchase — chicken tinga tacos, scrambled eggs, cheese plates, etc — typically costing $12-$15. Non-alcoholic beverages (soft drinks, juices, coffee / tea complimentary). I bought a tasty IPA ($12). Wine and spirits with mixers are a similar price.
The toilets: Three in Economy cabin — one up front, two down back.
Luggage: An extra US$30 for a checked bag up to 25kg. One carry-on bag permitted free.
The airport experience: Pretty crowded but surprisingly smooth. Longest queue was the bag drop but that was only a five minute-or-so wait.
The bottom line: This was better than I remembered UA domestic being when I was last on it, a few years ago. It's a relatively long flight that crosses the continent and links two popular destinations. I would (and probably will) fly this again.