Yeah but in the end, it's still a 10v10 map. Not the MMOFPS or whatever such games like to call themselves, played too many of those tbh.
There's a reson for 10v10, it works in games. Start adding more people and not only do you start getting laggy performance, but everything gets harder to balance (i.e. things devolve into spamfests) and teamwork becomes almost impossible to manage and organise causing frustration.
Why do you think WoW has moved from 40 mans down to 25 and 10man raid groups? 10 people is about the right amount to keep a game fun.
It's a nice alternative to TF2, similar actual gameplay but with added character flexibility and clan atmosphere/rivalry without having to sink hundreds of hours of grinding in like a normal MMO.
I tend to split my evening time between TF2 and GA fairly evenly.