I've got to the point my squad is lvl 220 and leveling past this point is just ludicrous. I need thousands and thousands of purple dust in order to upgrade each girl, and they come at 100 a pop only from one of the girls I can beat up in the events. Considering the downtime of events, it's unlikely I could upgrade the squad sooner than 2 months time, that's two months of basically not progressing at all.
There should be more sources of dust around.
Also, I don't see what the angel does. I've spent millions of gold on her, and I notice no difference using her and not using her.
It'd be nice to have a system to fast upgrade equipment. Clicking 500 times per item is quite tiresome and unless you're being sponsored by mouse companies, it's a bad trait.