Quite good, Ciro Santilli played this a lot in 2021/2022, his user ID: ofo5fNy7wRNC1Cw94YVB4KMOW5f2.
The physics not as good as the original Mario Kart 64, and it is notably missing jump gliding, and generally not as sharp! But it is really not bad.
Some of the weapons were too useless that you are just better firing them straight away at wall immediately to get something better, they could have a little better balancing there. I'm talking about you gatling that takes 10 seconds to finish firing, and does not kill enemies immediately. You are better off just firing that gun immediately when you get it to be able to get another gun ASAP. They seem to have done some balancing there however.
It had no chat option, but in a way it was cool to be forced to communicate non-verbally with people whose usernames you got familiar with. Funny you can love people like that, without ever talking to them. The best way of doing so being tea-bagging by going back and forth on a player after winning.
Performance was sometimes a problem. When Ciro tried it again on December 2022, it was unplayable due to the impossibly large lag. Tiings were much better again in 2023 however it seems.