Well done. Here are my thoughts:
Gameplay feels pretty solid, maybe a little bit floaty but it is an asteroids game. All of the powerups feel solid and the weapons are fun to use.
As for improvements - It would be nice to have a way to view global leaderboards, perhaps separated into daily/weekly/all time categories, so that you can see all of the scores and not just the next best one. More weapon variety would also be nice.
Otherwise, really solid job. I'm looking forward to seeing where you take this. 5/5