For her to rely on such a small army, the teenage demons would probably have to be pretty powerful. That or she was planning to make more in Equestria. So apart from creating a semi-poweful(?) army, we saw her crushing some concrete and mind controlling large amounts of people. That doesn't really give a good image of her full power.
There's a similar problem with a lot of other characters too so it's difficult to draw comparisons. What makes her demon form different from other powerful creatures however, is her obvious weakness, the crown, which makes for an easy target so she has that as a disadvantage against others.