I've played on friends' copies of Halo in the past and it is a great social game. I am not very good as my reactions are fairly slow, but it's like playing paintball games with rockets and grenades, all from your sofa.
Having never heard of forza before I presumed it would be a rubbish car game that is difficult to control. I was wrong! The graphics are impressive, the handling of the cars on easy enabled my young nephew to play easily, and there is a massive selection of cars. One of my favourite car games on Xbox at the minute!
A second controller - always comes in useful when mates come around! (nothing much more i can say about that - would be worth considering purchasing a charge and play pack in addition though).
Ultimately this pack provides great value for money.