You know that SELECT changes the speed of your ship, right? Just like in the Gunhed/Soldier series. On the fastest setting, your ship is anything but "slow."
The gameplay in Terra Cresta II is very dynamic and changes based on how many "F" powerup gels you have, which vessel add-ons you have and how you've set up your ship formation. Experiment with these things and the "I" button to see what I mean.
It's funny what you say about the sound, or more specifically, the music. At first it has a very abrasive quality to it. To me it sounds like what you would get if you mixed the Genesis sound chip with the NES sound chip. Play more into it and you'll see what I mean. After a couple plays the music really grew on me, and I really like the tunes now.
The game used to sell for around $200, "back in the day." I bought a new copy within the past year for $70 U.S. (it was from an eBay seller in the UK, go figure).