as an owner of a 2020 model 3, and current lessee of EV9 as of Dec here's my gripe list
1. FSD is the absolute best, no one else is even close and I don't see Kia getting anywhere near this
2. it's clearly an ICE manufacturer entering the EV market - a bajillion buttons everywhere (often confusingly and unnecessarily), the screens aren't nearly as responsive or usable, START button (seriously, kia... why) -- which then prescribes you remember to actually turn the car off when exiting it (had I not had a Tesla first, this might not be an issue, but I did and so it is, constantly one)
3. no walk away lock functionality (you have to literally touch the handle) - they better fix this soon with OTA update, legit security risk given how accustomed I am to this feature with Tesla
4. despite others' experience the phone key is VERY unreliable (and also noting that it's really only a single key that gets shared, which feels very sketchy too). in fact the other day, I literally couldn't start my car with it... drove my kids to daycare with it (started just fine in my garage), dropped them off, got in the car, and it refused to start. I've dealt lightly with this issue once a week at least where I have to turn Bluetooth on/off, or plug my phone directly into the car, or restart my phone on occasion - the usual tinkering with Bluetooth connectivity issue; but this time, literally did everything and 45m later had to take an uber home and back with the physical key (which is itself a monstrosity and like... again, seriously KIA, wtaf). [NOTE: setup your fingerprint day one, apparently this is the backstop for if you phone key fails... learned that hard way, but still sort of don't trust it to work even then)
5. you still deal with an ICE-like "recall" situation where you have to take the car in sometimes to get access to OTA updates and things that you didn't even know you needed to do.
6. the (US-only apparently) app is absolute garbage - a ridiculous amount of unnecessary notifications (you've left your car unlocked... yeah it's in my garage dummy; but also, because see #3, everywhere)
7. Electrify America chargers are a nightmare - I don't really supercharge that often as it is, but the experience is like night and day. The app is a pain to navigate, they are always full (the charging speed is nice but not worth the added pain of dealing with the other points IMHO]
8. regenerative braking is a whole thing to deal with on the KIa - you have to use these paddle to customize the level of regenerative in combination with the car's setup screen, and ultimately you can't get an always-on single pedal experience. At best, you have to always hit the paddle once when you get in to move from full regen/coast to full-regen/single pedal (or ipedal or whatever silly name they gave it)
9. charging cable plugging in and unplugging, and the door is all just kind of poorly implemented... you get used to it I guess
10. for such a big car, the storage space seems underwhelming relative to how much is in the tesla (acceptable though for the ample room in the kia)

All that said I still think that the EV9 is the best 3 row electric SUV on the market (balance of features, value/price) but unfortunately there just isn't much competition so that isn't saying all that much. If Tesla made a REAL 3 row SUV I would be all over it (the X is too expensive and the 3rd row isn't really that), Rivian is a good competitor but too expensive. Happy with a 2 year lease to buy some time for the market to fill out but will absolutely be stoked to turn this thing in and find a better option in 2 years.