Huh? Truxton's great, one of Toaplan's better classic shmups! I think the Genesis version of the soundtrack is really good as well. It's a great version of the arcade music, pretty catchy stuff. Remember though, Truxton is a 1989 Genesis release -- it's a very early title. It's probably my choice for best Genesis game of 1989, too. (As for that PC Engine version, it released three years later. And while its music might be even better, the graphics aren't (they're equal at best), and they spiked the difficulty level up way too high.)
As for the gameplay, it's not really unique, no. It's a Toaplan game, and plays a lot like many of their other shmups. Truxton distinguishes itself from their others in being set in space, while Toaplan's other shmups were pretty much all land-based up to that point, and in its extreme difficulty -- Daisenpuu, Fire Shark, and such aren't nearly as hard as Truxton. Twin Cobra iscloser to Truxton's difficulty level, but even that might not be as hard, unless you play the somewhat broken Genesis version of Twin Cobra that is. Play NES or PC Engine Twin Cobra and it's clearly not as hard as any version of Truxton. Truxton's Japanese title, Tatsujin, means "Expert", and an expert-level challenge it is indeed!
The PCE version is only for masochists with more money than sense, though. The Genesis version is more fun to play; it's really hard, but not as excessively so as the PCE version. As for the music, yeah, the PCE music might be better, but even if it's harsh-sounding, I do really like the Genesis soundtrack as well. And I imagine that the Genesis soundtrack would have been better-optimized had that version released three years later too, like the PCE version did...