Here are my thoughts:
- I'd second the suggestion to remove the health bars. It's understood in SHMUPS that enemies sometimes take multiple hits. Players don't need the bars, and they add so much clutter.
- What are all these little icons/numbers around the Level/XP plates? Are these necessary? Could they just be shown at the end of a run instead of always?
- The harsh black outlines around all your text are not visually appealing. Consider a drop-shadow or something more subtle.
- Remove the 'Wave' counter from the constant UI and just show it centrally at the beginning of each wave.
- "Kills" doesn't need to be so big or central, even if the goal of the game is getting the most kills before death.
- Is keeping track of "Kills" even valuable when you're keeping track of "Score"?
- I have no clue what the little yellow... pill in the top left is for.
It's certainly not the worst UI I've ever seen (or shipped a game with
), but it's a little visually noisy.