She COULD of been good, but honestly her redemption arc was very weak and she's obviously just a replacement and acts like pre-princess Twilight. Not to mention she gets away with a lot of stuff that she shouldn't, like brain washing Twilight's friends and then swapping Luna and Celestia's cutiemarks.
If you want a redemption arc done right, look at Sunset. The school was still wary of trusting her because she DID do bad things. However, Starlight's village just insta-forgave her even though she didn't do anything to make it up to them.
And quite honestly there have been situations where they made her the only solution when it shouldn't of been a case. Like the season 6 finale when EVERYONE, Mane 6, princesses, Flurry Heart, Shining Armor, were all taken out off screen.
So yeah. Could've been good but it wasn't handled well comparatively.