[Zooko]

The two-vs-two format is excellent! The games are fast as furious. You get to chat with your partner so that you are socializing with your friend or relative instead of playing a computer game all by yourself. If one player is unable to play his turns his partner can do them for him. Strategies can be more varied since one team member can help the other one out on his weak points.

In general, the two-vs-two format is a superb format. The only drawback that I can think of right now is that there aren't very many maps that are the right size and shape for 2-v-2.