On Dec 5, 2014, I upgraded from Mathematica 9.0.1 to 10.0.1. Mathematica 10.0.1 had so many bugs, was so unstable, I could not even use it. I wasted hours trying to figure out the problem. Eventually, on Dec 15, 2014, Wolfram Inc. offered 10.0.2 on my Wolfram User Portal. I am currently using 10.0.2 on Windows 7-64 Pro and it is stable. The last time Mathematica 10.0.2 APPCRASH'd was June 17, 2015.

What is the stability of Mathematica 11.0.0? Does 11.0.0 APPCRASH a lot?

I am considering upgrading, and not waiting for 11.0.2, because yesterday I received this Wolfram Inc. email:

    "I can provide your upgrade to Mathematica 11 for only $95.
    The upgrade price will increase to $150 effective October 1,
    so this would be the best time to upgrade your license. You
    can upgrade in the webstore now or contact me directly to
    process your order:"

I was going to wait for 11.0.2 to be released. However, the above price increase is making me consider the upgrade earlier than I wanted. I do not want to install 11.0.0, only to discover it is unstable and then wait for Wolfram Inc. to release 11.0.2. I do not want, and I do not have the time, to deal with bugs anymore. As an example, Continuum Anaconda Python APPCRASH'd Nov 2015 and has been nonfunctional ever since. I have not reinstalled it because it will take all weekend to uninstall/reinstall and tweak.

Dan.