It's a very challenging but also very fun and unique game.
Some of the later encounters can drag on for a bit due to the high wave count and it can be crushing to get partway through and then lose your rank 2 weapons and unique tire sets.
Late demo foes tend to withstand a huge amount of punishment unless you equip a rocket launcher and put up with the subpar accuracy at anything besides point-blank range, and it's practically necessary because you need to take down individual cars as quickly as possible to reduce the number of guns firing on your car at the same time.