Pretty nice, I like it. It misses some features though, like you can have more than 3 players for a 3on3 if you change them after or in maps. You would also have an option to assign players individually to the maps if you add that. But you could automatically assign players from one map to the next so you wouldnt have to enter the same name over again but could just change it.
Also no limitation to the number of maps and the game mode (including 2on2/3on3/4on4 etc.) would be cool. The ratio of won maps : lost maps will always give you the result.