I'm mostly intrigued with two things: whether the 250 nit screen is as good as the 400 nits, despite the lower brightness (the 400 nits includes the obligatory IR camera, which raises the price substantially).
And also the fixed battery. I'm still working with the t440s and even though the single battery of the t490s is supposed to have a better runtime than both t440s batteries combined, it was good to be able to remove one battery and save it while the computer was on mains.
Personally, what would interest me in that computer is the weight, the better keyboard (I type a lot) and the very long runtime. But I totally get why people are mad about the low maintenance capability. I only changed the SSD on my T440s but yeah, having soldered RAM is really pushing to get more RAM "just in case", even if we don't necessarily need it for office work.