Coaster brake is a great idea. Simplicity. Cheap. Built in brake. All the disadvantages of single speed and fixed gear rolled into one!

I've been riding a single speed coaster brake exclusively for the last two weeks. I'm loving it. I did add a front caliper, however. I'm way too attached to front brake to give it up, use it almost exclusively. Just today, I did find how well two brakes work vs. one when a car made a abrupt right turn right in front of me.