I think charge works exactly as it says and the advantage is clear.
You move at least 2 squares up to your speed, provoke OA and then make a basic melee attack. You get +1 to your to hit roll. Pretty simple.
The advantages are being able to move at close to full speed and still make an attack (with a bonus). Name another way a character can move like that and attack. If the OA wasn't there, then what is the disadvantage if there are no other monsters around when you move?
Basically, if you want to move and then fight your moving once, provoking an OA and then getting a standard action.
Or you shift once, then get a standard action.
Or you can move then charge, getting a +1 to hit but provoking a OA.
The OA represents the opening your providing to your enemies from your rushing in. The +1 to hit shows the bonus you gain from your momentum.
If you ask me, Charge is simple and clear. People are just trying to find a way to make it more powerful than it already is.