Is this a good yugioh dark deck? Please give reasons for your answers?

I really like your deck. Dark Armed Dragon would not be a good idea since you might not have him in your hand when you have exactly 3 Dark monsters in your Graveyard. Overall, this is a good Dark deck. I would've listed the 2 Mystic Tomatoes and Newdorias as 2x Mystic Tomato and 2x Newdoria.