It's a lot less invasive in places with really cold winters. :) And besides, I have a tiny garden. If it starts taking over next spring, I can pull up as much of it as necessary to keep it against the porch. It spreads by seed, not root, so pulling it up is easy. Bindweed, now - that stuff is the devil in flower form. It's really pretty, but if I could eradicate it, I would.

I checked with my neighbours before planting it - neither of them care if a few vines of morning glory end up in their gardens, so I'm good there, too. I like a plant that can take care of itself. :)