Why would it be facing west? So its debris would land in China? Look at a map. Why pull things from your nether region? The flightpath for the rocket has been known for weeks.
Er... Haha.
NK presented an intended flight path, however some real rocket scientists analyzed the proposed path and determined it could not possibly result in the orbit NK claimed to want for its payload.
Also, these things go wherever the heck they want when things go wrong, so the flight path could give a hint as to how early it went bad. Media reports state that the rocket failed WEST of South Korea, indicating it was launched south-southwest, not southeast or east like the last couple of big rockets they've launched. If the missile (rocket, whatever) went stupid early on and it looked like it might overfly China, then it is possible a self-destruct was triggered.
Having lived in SK for a bit over a year and seen the NK's best game, my initial assumption is that nothing at all went right other than it didn't blow up on the launchpad. Launch, trajectory guidance, and eventual breakup before it even cleared the Korean Peninsula, were probably all FUBAR from the beginning. The invited visitors weren't even subjected to the merest hint of clean-room procedures when taken to go look at the thing, so the whole system top to bottom was likely fatally contaminated with dust or other contaminants that we've known for decades will cause these things to fail...
The best part is that the cost of that little PR stunt could have fed and kept warm almost the whole country for a few winters.