Grape Shot is an upgrade for the Monkey Buccaneer in BTD4 and BTD5. Grape Shot adds a volley of deadly sharpened grapes to the attack. The grapes, once fired, have the same capabilities as the darts from an 0/1 Dart Monkey as they can pop 2 bloons each.
In BTD5, the grapes are purple, where as in BTD4 the grapes are green. This is purely an aesthetic change.
This upgrade works very well when the bloons are close to the Monkey Buccaneer.
The target "close" is therefore effective for Grape Shot Buccaneers.
This upgrade is better than buying 4 separate Dart Monkeys as Grape Shot is cheaper.
However, the grapes do not independently target bloons as Dart Monkeys would.
In BTD4, the grapes have eyes but the grapes in BTD5 don't.
In a 2013 update, all grapes now pop 2 bloons each instead of 1. This is why the Grape Shot price had risen from $300 to the current $500 cost today.
In BTD4, when purchasing the Grape Shot, the Monkey Buccaneer gets 2 more cannons. However, in BTD5, there are no added cannons to the Monkey Buccaneer, instead having a pile of grapes in front of the monkey.
This upgrade helps the Monkey Buccaneer immensely when bloons are spaced out, as the darts have a tendency to miss some bloons.
The grapes in BTD4 more resemble olives than grapes.