At its best this deck can spit out a Hand of Emrakul on turn 3: Turn two play a two-mana Spawn token (either Spawning Breath or Nest Invader) and on turn three play Brood Birthing - sac four spawn for the Hand.  Even if that doesn't work out, though, the deck tends to be (relatively) quick with the Eldrazi.  I tend to have more problems finding Eldrazi than enough mana to play them as the game goes on. 

Oh, and always carry your other Eldrazi with you when you play this deck.  If the game runs long the Spawnsires will reward you with an army of terrors.