Is this a good YuGiOh Deck?

It's good. Minus Obelisk ,Slifer and Ra. If you plan to duel in some tournament, those cards are illegal. Just because there is no way to summon them, except Obelisk. And there is no way for Ra or Slifer to gain any attack points. Ra, Slifer and Obelisk are, more or less, collector's items.