That is not the only new stuff in Worms World Party, there are alot other additions.
If you don't own a WWP cd you might as well buy it for $4.
But don't expect it to replace your WA playtime.
You can play around a bit with the missions, and the wormpot, but i'm sure you'll switch back to WA right after. If only for the faster working menus.
I wish they would put W2 on steam though. I wouldn't mind playing that game again. *(too lazy to find CD and install it lol)*