It's not traditional to have guitar in an orchestra, but it works. Sometimes you just need that guitar sound, especially with video game music (see Video Games Live with Tommy Tallarico).
Your covers are pretty good! My favorite is Dragon Roost Island.
Some nice covers you've got in here! My only complaint is the presence of guitar leads in a number of the tracks, which threatens the very foundation of the album's name (Great Video Game Orchestra) XD Jokes aside, it's a nice collection of faithful arrangements that I'd predict to have a decent rate of downloads.