Eh, the flag is useful, but it also is a close to 100% TUs "weapon". I used it in few battles to get snipers in position and able to shoot on T1, but after that, the little bit of extra mobility for a group of snipers + 1 flag gal versus 1 more weapon gal just didn't seem to be much better. And I had to move all my other gals out of the way first, otherwise they'd lose a chunk of energy for nothing (which, with some armor, is annoying to lose).
In the end, it felt like trying to exploit a mechanic or solve an equation, the later of which I do routinely for work, not like playing a game, so I quit. The flag is cool and quirky, but it's not for me.