If you're even the slightest bit as geeky about video games as you are about music, you must have heard one of the several bands whose raison d'etre
is creating guitar/bass/drums covers of old Nintendo cartridge themes. The fact that there are now a handful of these groups either indicates the existence of a viable, long-term, hitherto underserved niche music-listener market or marks this phenomenon as an easy-to-bandwagon fad.
Either way, the idea here is to evaluate The Advantage as a musical effort and not as a nostalgia trip. Imagine a listener who has never heard these songs before, and who will interact with them as if they were novel compositions designed for the instruments that are playing them. Would he/she be moved? Probably not. The "Intro and Stage 1" theme from Castlevania, when you get right down to it, is just a sort of inoffensive, utilitarian melody. The Advantage go to some trouble to try to funk it up with a bassline and syncopated drum fills, but there's really not that much to it.
On the other hand, as a nostalgia/geekery exercise, The Advantage has its moments. Every late-20s/early-30-something male you know will no doubt unconsciously begin tapping out the secret "30 lives code" at the onset of Contra's "Alien's Lair & Boss Music", and "Kraid's Lair" will have every Metroid fan's toes a-tappin'.
The Advantage do a credible job of translating these songs into a conventional rock-band idiom. The only question you need to ask yourself is whether or not you want to hear that translation.