When not connected to an external display I don't have any issues. It seems to be triggered when using an external display connected via mini DP. In addition I notice the issues are more pronounced when that external display is run at very high resolutions. I have reported it to Apple, and I know other people in the threads have similar issues (Intel 4000 with external display), so I am hoping that there will be a future fix. If not, I will just continue to use Windows 7 on that same system which has problem free. I would rather use Mac OS X, but at this point forced to use Windows 7 to work around the issues I have.
I agree, not everyone with that model is having issues. I think issues become exposed in specific setups, like me using a Macbook Pro 2012 with a 30" external monitor at a resolution of 2560 x 1600. Other times it seems to be a software specific like iStats, Little Snitch (for example of kernel crash:
https://www.obdev.at/products/littlesnitch/releasenotes-nightly.html), or Fusion. With so many different configurations of hardware and software, I am sure it is hard to catch everything during beta. Reading some of the responses in this thread people are so high up on Mac OS X they think it can do no wrong, and if people are having issues it must be a hardware or software issue, no way could it be Mac OS X since they don't have the issue themselves. I have a Mac Pro that runs Snow Leopard and it is rock solid, while it has been nothing but random issues with Yosemite on two different Macbook Pros. I do admit El Cap is trying to fix those issues, and the 10.11.1 seems to be a step in the right direction (fixed some kernel panics people had on the forums). My hope is by the end of El Cap (10.11.8 or whatever) it becomes a Snow Leopard like release, but it is not there yet, and the people who say it is have just been lucky not to be running a hardware configuration or software configuration that is causing OS issues.