The Big Bang is a very slow moving projectile that can absorb a lot of hits.
So while you might not be able to quickly punish enemies from afar,
it's absorbing/shielding nature can make it act like a moving wall of death,
though the opponent can very well jump over it. Also, you can keep charging the move for as long as you'd desire,
making the Big Bang orb grow in size up to two times.
For about 2 seconds after Vegeta launches the Big Bang, you can input the QCF+P command to have him manually detonate the orb, causing a lot of damage.
In the latest update to Majin Vegeta, the Big Bang was recoded to work more like Piccolo's Special Beam Cannon;
starting out as a Lvl1 move, but draining any remaining power bar you currently have left, making it stronger,
boosting it up to a Lvl3 move.