Due to the relative smallness of the map--and the excessive amount of cloak-enabling weeds--the rectangular-shaped arena offers plenty of nasty ganking opportunities. And with only two towers between you and the base, rather than the standard three, the whole match can be over in the blink of an eye.
The fast gameplay and lower player count is something that League of Legends needs, and this map fits the bill quite nicely. Apparently it's going live in this week's beta update, so testers will get a taste fairly soon. For the rest of you, the above sentences will possibly become intelligible when the game officially launches on October 27.