Normally I don't respond to these posts, as I probably become redundant, but this is a childhood classic. I was very young at the time this set came out, and it immediately captured my imagination. My brother owned it, but I liked it so much my parents bought another one for me.
The minifigs are great, along with the foilage. As for the catapult, it does seem kind of useless. I used to explain the catapult like this.
Whenever someone tries to attack the forestmen, there's lots of traps awaiting them. One specific spot of forest ground is marked. The catapult is positioned so that if a soldier walks on that mark, he'll be in a spot where the catapult can knock him right in the head. If he's wearing a helmet, it'll probably just leave a mark. Without a helmet, he might become unconscious. Whichever the case, the sudden stone throw would lead to a bit of confusion for the enemy. Combine that with other traps, and the forestmen are set. On a side note, the soldiers attacking are going to be moving considerably slow, considering they can't see their enemy, and they're in unknown territory.
Even that explanation is kind of bad, but I'd like to see someone try to explain the catapult on top of a horse in KKII.
9/10 Set. Good price, pieces, and figs.