Alright, we played through this one today in testing and all I can say is that it's a killer sniperfest. And aside from being a killer sniperfest it is just shooting each other inside of a box. Once we realized that leaving your spawn room was instant death we just set up sentries inside the spawn and waited to mow down the other team. There's no real tactical element to the map at all, you either die immediately from sniper fire or jump around a big wide open space trying to pick each other off.
It would have been more interesting if you could get up into the seating by rocket jumping but not even that was allowed so you were restricted to your wide open square and the gameplay value and novelty music died fast. The rounds lasted less than a minute and after one round each side we quickly moved on to the next map.
As to how you can improve this I'm not really sure, I would definitely add some more detail into the area in which you are battling, perhaps some side passages that wrap around the actual arena so you aren't all running straight into the line of fire. More interesting things would be locker rooms to each side of the arena with passages between the spawn and those also, but pretty much ANYTHING other than just being one big box would be an improvement.
EDIT: OH, forgot to mention, the music got annoying super-fast. I know someone here posted that it would be epic to have pokemon music playing in the background but it kind of wasn't very epic at all, just irritating.