If it works properly, it's not bad. Keep in mind it's rear wheel drive until after the rears slip. Then it transfers power to the front. A properly working case should do that fast enough that you probably won't even notice. As they age though, it takes longer for the transfer of power to happen. Which means your rear end might slid all the way out before it sends power to the front. And then there's the transfer cases that don't work at all because the po neglected it or put the wrong fluid in it. Which is quite common with that case.