I went through MCO last month and used these new kiosks, and got through in 5 minutes. Since ESTA was introduced, the delays at US Immigration seem to have improved significantly, and I have rarely had to wait for more than 15 minutes or so (which is about the same time we Brits have to queue to get back into our own country!).
What needs to be improved is the delays for outgoing flights. Last 2 times at MCO took an hour to get through security. This badly lets down what is normally an easy airport to use.