i'm half-responding to some of the comments in this thread...
regen braking - never had this before but I've driven racing clutches (lightened flywheels) and the driving/deceleration is very similar. adopting "one-foot" driving wasn't terribly difficult. what gets me is when I drive my GF's ICE car and it just keeps coasting. makes me REALLY uneasy.
SR+ sound system - honestly for me, it's very clear, there is no distortion and the range is acceptable. i would, however, like to enhance the experience by adding a subwoofer and enabling the rear speakers. FWIW, it's lightyears ahead of the car i came from.
accessories (additional purchases) - i kind of started buying things for the 3 before getting the car, but i had no idea that it didn't come with even basic floormats. this was wild to me. i'm kind of glad not to be financing things i can just pay for up front, but floormats, really?
piano black - i've avoided cars because of this interior design choice. i've seen what they look like after years of use. no matter how nice you are to them, they'll get swirly and scratched.
interior trim - the door panels are a fascinating and to me screams inexperience in the auto industry. i wouldn't be surprised if the door panels fail after 10 years (deteriorate).
frunk - i really wanted it to be more usable. it's difficult to close, it gets hand prints all over it, it's smaller than usable and the emergency button can pose a problem if you have something rolling around in there. one day i had the frunk open because my kid was putting his drones in there and people were stopping to make sure my car was ok (hood open = engine trouble). i laffed.
"toolbox" - i actually get more use out of this neat little area. would be nicer if it were the size of a tire so I could decide to fit a spare if i wanted to.
i think for me the most surprising is how much these seats don't breath. i've heard people yelling for cloth seats but honestly some perforated material would fix a lot of issues. also i'm starting to realize they are too soft. i didn't believe some of the naysayers on here but dang, i hope these guys last long enough.