Experienced gardeners have a strong love-hate relationship with violets, and it all depends on where they are planted. Of course, everybody loves the flowers. Just keep them out of your regular flower garden, and use them under trees, in front of shrubs, and other places for patches of color and borders of groundcover-like violets alone. Because they seed and spread rapidly, and if they spread throughout your other perennials, and in a year or two, you'll have a big job pulling them all out and cleaning everything up.
But just look at those flowers! Who can resist? Plant yours where you want them to spread, and you'll love them forever.