I have a U1273A for i think over 5 years and i used it a decent amount. No burn in is visible on it, tho i do have the display brightness set lower as indoors its still very perfectly visible on lower settings and it brings the battery life past what some LCD DMMs get on 9V batteries.
Yes i would expect the display to deteriorate somewhat in the span of 25 years, but even LCDs sometimes start failing after such a long time. Out of all the DMMs(Like 5 of them, not counting benchtop ones) i have i keep using my U1273 the most because i really got used to how well readable the display is compared to LCD. Yes outdoors its not so great but i can just use one of my other 4 DMMs for the rare occasion i might need to measure something outdoors, this is a meter that excels on the electronics workbench.
The meter is still holding its calibration down to +/- 1 count of the last digit on DCV, DCA and Ohms after all these years.