Thanks for the feedback everyone :)
@AidanAK47 - The ship was supposed to be able to alternate between the speed it has now and half of that for more precise dodging, but it got botched in the repository and did not get added back in before submission.
As for the enemies disappearing, this was simply because we didn't have enough time to implement an explosion. The sound effect triggers, but we didn't have an explosion animation to use and we ran out of time to make a decent one.
Our initial concept included much more elaborate levels and boss battles, but again, we ran out of time. We actually made a system to allow level creation using Tiled to define enemy spawn points, but due to real life things some of our team got called away and most of us work on the Monday after LD, thus making the Jam effectively 48 hours anyway.
I definitely agree with your points though. The ship should move slower like it was initially capable of, there should be legitimate explosions not just for enemies that explode, but for the little missiles that get fired, and there should be actual levels with bosses.