I just finished my 1000/1000 on this, and I must admit, this game really redeemed itself in the second and third acts.
I know I stated in an above post the game was lacking storyline, and in the first act, that is true. However, after you move to Florida, the storylines (all from the movie, and done from a unique perspective, much like the horse mission in the first GF game) pick up and keep the game from getting stale.
I really have to recommend this game to any GTA, open world, or Godfather fan out there. If you enjoyed the first game, GFII improves upon the basic structure of the original, and is well worth any current price tag.
I paid a full $60 for the game, and at about 16 hours of single player and unlimited multiplayer, that seems like a fair price.