No RPN. Every modern graphing calculator needs a mode (doesn't have to be the default) with RPN and a visible (4+ entry) stack. Once people actually learn how to use that for rapid, efficient calculations, they won't go back, but they never learn because all the major calculators don't even offer it as an alternate mode. That's the killer app for "graphing" calculators, because they can show multiple stack entries.
RPN may not be useful for math classes, which tend not to have as many problems involving many sequential calculations, but it's extremely valuable for science and engineering.
Bear with me if you’ve already seen this comment, but I dug out my old TI-89 a while ago for some reason, and all I had to do was plug in four AAA batteries and it worked.
If it had been fitted with a rechargeable battery, 30 years ago, even assuming it was still functional, I would have needed to recharge it... but with what?
Now we have USB-C rechargeable AA/AAA batteries, so there’s really no excuse.
Non-user-replaceable batteries are terrible. It turns devices into e-waste. I wish device manufacturers would understand that. I wish consumers would understand that.
Device manufacturers want you to buy another one. They understand. Consumers, not so much.
I mostly remember playing games on my TI-84 in high school. We used it in class maybe once or twice. None of my college classes allowed graphing calculators on tests, so ironically I had to buy a "dumb" calculator even though I owned the fancy one.
I think it's more of a not-entirely-rational appeal to parents: "if my kid has a top-notch calculator for high school / college, maybe they're gonna be better at math". And kids did not object, but in the end, mostly just sideloaded games and horsed around.
Does it have a CAS?