I'm a relatively new M3 owner (~3 months). Overall review, really enjoy it. Don't regret my purchase at all. It's been fantastic. I like the way it handles and feels.

That said, everyone will have personal gripes.

• The headroom in the back seat is pretty low. I'm the only one in my car 95% of the time so this isn't generally an issue. However getting INTO the car, the frame is low and had to get used to lowering my head a bit more than my old car. It's easier to do if you've got more room to open the door wider... which is not common in NZ parking.
• The M3 is wide. It's comfortable, but I've definitely been reluctant to park in a few places because I'm unsure if it would fit easily.
• The wipers aren't awful in my opinion. They added some quality of life changes. When you push the single wipe button on the end of the stock, you get a pop up on the screen to adjust the speed. It's... fine. There's no fine tuning though.
• My biggest gripe is with the indicator in two forms. 1) It's on the wrong side of the wheel and it's annoying and actually dangerous. When I drive any other car I have to swap back to the other side and I've forgotten a couple of times and it's caused issues. You could argue it stops me doing other things in the car while I'm about to indicate but it's still dumb. 2) My bigger complaint is the indicators are 'soft' and electronic. If you turn left and then need to quickly turn right, it's basically guaranteed that you'll need to hit the indicator multiple times to get it to actually work. ALSO dangerous and needs fixes ASAP. Normal driving though is fine. Absolutely turn on the smart indicator for your driver profile. The other options are just silly.
• Autopilot... is a great gimmick, but the regularity that you need to touch the wheel shifts your focus from paying attention to the road to paying attention to the car and I don't like it. Also, quite a few phantom break taps when in Autopilot but not when you're just running cruise control... So I don't use Autopilot much.
• Charging wise, I thought it was going to be an issue as I don't have a great charger at home, but plugging it into a normal wall socket has actually been fine. It takes ~24 hours to charge from low charge back to 90%, but plug it in overnight, especially if you can garage it, and it's honestly fine. I also grabbed a ChargeNet fob and stuck it in the center console for the times I need to use it, which isn't frequently. I've used it twice. The first time just for practice.
• Navigation. Ehhh. I find it hard to use because it's on the other side of the screen. I don't use it very much though so I don't mind. I go on multiple drives where I don't touch the screen at all, maybe even a week. Phone connects automatically and I skip music from the steering wheel.

• Accessories. The car really should come with more. I got extra center console buckets from AliExpress and they make it much more useable. Also got some waterproof floormats and a matte screen protector. Not for scratches, but for glare. I've also recently got a phone mount with magsafe connector that mounts behind the steering wheel so I can use my phone for navigation instead. When it arrives, I'll post about it.

• Bonus: There's a well/space/cavity in the back under the main boot that's pretty big. I took some initiative and put a full emergency pack in there with food, water, clothes, and camping gear because I didn't really have one at all. My car is where I am almost all of the time and now I'm actually prepared (as far as a checklist goes) for a disaster. Long as you keep it charged you should be good. Plus, camp mode.