Several other people have posted comments that the sound effects are indeed of a low quality, or "crappy" if you prefer. The laser sound effect has been mentioned several times as being particularly poor.
However I was not referring to the QUALITY of the sound effects, but to the fact that sound effects in GENERAL are a poor substitute for a rocking soundtrack in a shmup. A shmup without music is just not a complete shmup in my book - is it just a half finished game that is waiting for someone to finish it properly by adding a soundtrack.
In fact, in shmups with really great soundtracks (which many have) I often turn the volume of the sound effects right down in order for them to not spoil the soundtrack.... never heard of anyone ever turning the MUSIC down in order to hear a few crappy sound effects though..