It can protect anything be it Enchantment, Creature or even Planeswalker (though it wont stop combat damage)
This is usually enough damage for game: just 2 2/2 creatures plus Craterhoof Behemoth (haste, remember) already adds up to 18 trample damage enough to finish off a slightly-damaged opponent
She isn't too shabby honestly, she does a bunch of things to generate little bits of value, so I think if you're playing something that can use these all pretty well (Naya counters maybe?) I think she's alright
It can deal with problem cards out of graveyards (Arclight Phoenix, Kroxa, and Storm the Festival), generate late game value, and gain life
And lo and behold, it made it into the set
If you have a mana source, an untap effect, and a tap effect that eventually ends the game, Gogo can get you the win