Really good! You managed to keep the essence of the game despite the simplifications you made. Was much more faithful than I expected actually! I like the little balance changes like Sogen being twice stronger and UFO turtle capable of summoning in defense. Evokes nicely the old yu-gi-oh spirit, and the game is reactive (doesn't drag like in the gba games). Also having music from the anime is a nice touch.
It's a little too easy however. I imagine it must be difficult to balance a game like this.