The main issues for hunters as multiboxers are:

1. Always having to face the target to dps.

2. Lack of AOE.

3. No wipe prevention in Instances, unless you go engineering.

4. Can't do heroics.

That said, they do offer pretty good burst damage for pvp, have great CC in form of traps, and customisable pets are pretty good too.

Cheers,

Stealthy