UA is a different airline for 1Ks.

Of course, you have the often indifferent service esp. aboard the planes and on the ground

But aside from that, you get treated much better. It makes a difference.

I got back from a trip to MEX and OAX (Oaxaca) and was able to skip lines and check in right away, saving me a lot of time. The 1K line was great and we sailed through as opposed to waiting for 30 to 60 minutes which I would have had to do otherwise even as a Prem Exec.

I used an award ticket and got a non stop flight back MEX-IAD after being waitlisted and got great seats even over a busy holiday weekend.

UA's service is very spotty but being a 1K is way better. Upgrades can be very hard on the most busy markets but as a 1K I have rarely not been upgraded compared to when I was a PE.