the ones I've tasted have been fairly yummy, sort of like an extremely fruity little mini-tomato. Make good pie also. I'm told that the poha jam I've had in Hawaii, which is *excellent*, is made from ground cherries. I believe there are different varieties though.
I've never grown it before but just today got my seeds to try it this year
Since tomatoes self-seed, I would imagine ground-cherries probably do too. Unless you consider volunteer tomatoes a noxious weed I wouldnt' think they'd be 'invasive' in most places though. Just guessing of course.