Wow! Thanks, that's a particularly glowing review ;)
Yep music-wise we definitely need more tracks in any future version. I think it fits the game well but a single track on repeat over 40 levels / 2 hours is bound to get annoying eventually, so in agreement with you there. I also wonder whether we could add difficulty levels or accessibility settings in future... so maybe you could choose the setting of your ship's speed. It would add replayability too I guess - players might want to retry all the levels in gradually higher speeds!
Thanks for the review and the useful feedback.