This is a good game, and I will definitely consider purchasing the full version.
However, there were some lag issues I had with the controls. Sometimes the movements didn't occur until about two or three seconds after I had already pressed the keys, which is annoying enough in the earlier levels, but absolutely unplayable when you start to encounter enemies (I suspect this is what some people meant when they said they kept dieing due to "horrible controls").
This aside, great job!