If you let it seed it will take over your garden, though it's easy to pull up when young as it develops quite long roots when older. Personally I wouldn't encourage it in any way 
I'm a bit suspicious of the assertion that it's biennial, the stuff that grows around my place (despite my annual eradication attempts) flowers in its first year.
People we do actually admire? Are there any?
How will things change if our summers keep getting hotter


