The customization is still impressive almost 11 years later - like others have said, no other game of this nature has nailed customization quite like APB for both vehicles and characters.
When the matchmaking works out, this game is just incredible! I've had some nail-bitingly close matches that have ended with a narrow victory or loss! That sweet spot is sometimes hard to hit, but it's so satisfying when it does.
Plus, I think APB nails the random moments really well too. I remember one time years ago where I was playing with some friends as enforcers - we were randomly put into a match and raced across Financial to catch up. The crim team had just finished their objective and were driving away with one of them carsurfing on top. I blindly took a jump off the highway overpass, suddenly saw this car of crims hurrying to their next objective, and managed to land squarely on top of the guy carsurfing. Unfortunately I lost my clip of that incident to a hard drive failure!