Main 3 advantages:
1/ No line streach so every litte knock gives a bleep.
2/ Thiner in diameter than an equal pondage line.
3/ Lasts for a good 3 years, then respool it onto another spool and use the other end for 3 years.
Disadvantages:
1/ Initial outlay 2 times more than Line.
2/ Subject to wind knots when casting if the spool is not fully wetted prior to 1st cast of session.
3/ If you don't slacken the clutch off you can get hook pulls when nearing the net due to the lack of streach.
4/ You MUST use tubing (use a pole threader to put it on)otherwise when the Carp roles it will scuff up its flanks severly.
5/ Advisable to where a finger stall when cast as the braid will slice through your finger very easly on an aborted/cocked up cast.
Having said the above I personally use braid and love it