In the city where I live, there are one-way lanes on either side of many largeish streets. Even so, every day you can expect to see people riding the wrong way in them. It's dangerous, and unnecessarily so.

I won't go so far as to say that I'm opposed to them outright, but when there's a choice between a street with a protected lane and a quiet street without one that runs parallel, I'll almost always choose the street without.