The butterfly bush performs as advertised, attracting lots of butterflies.
Hummingbirds, moths, and bees love it too. Ours is outside our kitchen, and I enjoy watching the activity out the window. But not everyone is a fan of butterfly bushes. They can be invasive, and while they do provide nectar they are not host plants for butterflies. Keeping the flowers from going to seed and planting other appropriate hosts plants can mitigate these problems. Invasive species can create all sorts of unforeseen issues, though, so in retrospect I might reconsider planting this bush.
I’ve learned the hard way that it’s best to cut the plant down almost to the ground in early spring if you want to keep it looking tidy. Right now mine is a bit scraggly, as I did not get to that chore this spring. I’ll remedy that next year, and fresh growth should improve its shape.