I always give songs a chance, even if they give me that "bitter beer" face when it first plays. I hate it when people call others close-minded or simpletons because they can't "broaden their horizons" to accept something they just don't like. The instrumental version of this song may be decent, while not incredibly groundbreaking. Still, it's a catchy ska/polka style spin on the game tune.
The vocals, however good the vocalist is, totally ruined the track for me. It reminded me a lot of how Japanese bands put vocals over video game tracks... just seems misplaced, unless they originally contained the lyrics. Now, had the lyrics been funny, as sort of a spoof song, it would've been mildly entertaining. But you just can't make fun of Ninja Gaiden. I think the only other instance where you can get away with alien vocals is if you can't really interpret the language of the lyrics (say, Latin chorus addition to One Winged Angel). That way it's an addition to the work, something that supports and refines the original piece, not vocal graffiti sprayed over top of the music, completely drowning out most of what was originally there for most of the listening experience.
Instrumental... enh. With vocals, pppppbbbbbttttt. However, I think any original tunes your band has might be interesting to listen to.