Short sweet solid shooter. You could do worse!
But the aiming is reasonable and the movement is crisp.
You could ask for more,but on a hand-held, you rarely get it.
Graphics are above average, and a lot less dark than many of the genre.
Some might find the AI not too "I" but what else is new?
I'd say this game compares favorably to the Metroids with better visibility.
It could use a little more variety, but on the other hand it's not DEVOID of variety,either. The threat/goal/gain factor (some call it "immersion", though on a portable, I think that's a myth) is just about right. It needs a few tougher "bosses".
Bottom line, I had a good time.
What else is there?