Something like this is really hard to say anything different about, it's Contra 3: The Alien Wars but with robot characters, so I'll put my Contra 3 thoughts below to explain the same.

I gotta say it's a really good game, but has a really glaring flaw. It's really pretty graphic wise, and it moves at a really good pace with a lot of options for weapons and combinations...but the difficulty is a bit scattered in places. I feel like the game never has a constant flow instead it kinda peaks and valleys at random spots be the stages or the bosses. totally not a bad game, but I always wonder why people say the original Contra was hard but they don't bring up how hard this game is.