If your Mac has been freezing up since you applied the OS X 10.11.4 update to El Capitan, then take comfort in the fact that you're not alone.
 
There are widespread reports of systems freezing up following the updates. The majority of these freezing system - although not all - appear to be 13-inch Retina MacBook Pros (Early 2015) and 15-inch MacBook Pro (Mid 2015).
 
The freeze-ups are also being reported by users who have installed the Safari Technology Preview Version 1 and OS X 10.11.5 Public Beta 1.
 
Here's a video of what happens:
 

 
The freeze-ups appear to be random, and they require the system to be hard rebooted to bring it back to life. Unfortunately, this is only a short-term fix, and some users have been forced to either rollback their systems to 10.11.3 using a Time Machine backup, or reinstalling OS X from scratch (both of which are time-consuming activities).
If you haven't yet updated to OS X 10.11.4, then you might want to hold off upgrading until this issue is addressed.

 With Windows 10 as an evolving OS, we may see the same type of behavior.

Tim Cooks is most regularly used a swear word in this house. Ever since he took over, things have been going downhill. Personally, I refuse to upgrade OS on my DAW - which ran Mavericks when I bought it. I made the decision before I got it that it would only run software that was contemporary to it.
 
The upgrade from Snow Leopard to Mountain Lion and Mavericks (in the hope that Mavericks would fix what Mountain Lion broke) taught me a lesson.
 
Given the option, I'd go back to Snow Leopard on all my computers - and the only thing I'd miss would be Air Drop. Logic X has been out for almost two years now, and even though it is an amazing program, it is nowhere near as solid as Logic 9 was after a few months.
 
Nevertheless, considering that the Microsoft Office apps which I use (Outlook and Word) crash every single day on my Macbook Pro - and that, quite ironically, the Microsoft Problem Reporter which is launched when one of the Office app crashes also systematically crash every time it is triggered, I am not yet ready to move back to Windows. ;)
 
 

I hear you, Rain. Time for SOS, Son of Steve, to step in and take over.

Rain
Nevertheless, considering that the Microsoft Office apps which I use (Outlook and Word) crash every single day on my Macbook Pro - and that, quite ironically, the Microsoft Problem Reporter which is launched when one of the Office app crashes also systematically crash every time it is triggered, I am not yet ready to move back to Windows. ;)

FWIW, I run Office 365 and run Outlook and Word every day.
Not a single crash... (running under Win10x64)   

I see that Jim don't pull any punches  I can respect that
 
Kenny

I don't think Rain's stability issues with Office have anything (directly) to do with Mac vs. PC.
IMO, Neither platform is inherently more/less prone to stability.
 
I do think running a Microsoft product on an Apple machine... there's less impetus to resolve issues.
Similar to running QuickTime (now) on a PC.
It's the computer version of politics.  
Oh, you're having security issues running QuickTime on your PC?  Well... you should be running a Mac.
Oh, you're having stability issues running Office on your Mac?  Well... you should be running a PC.
 
 
 
 

Things I lost with the Win10 upgrade:
 
Bejeweled Twist [sob]
 
Six weeks use of my Tascam US-16x08 [driver extremely stable now; easily better than under Win7]
 
My old, buggy ATI video card [replaced with a terrific Gigabyte nVidia card]
 
Softube still struggling to get their x64 plugins to work [like the Drawmer S73]
 
 
Things I gained with the Win10 upgrade:
 
Able to disable internal audio
 
Stability [it's improving, not getting worse]
 
Speed boost
 
Windows Defender good enough that I canceled my Kaspersky subscription [Win10 shuts down WAY faster now]
 
Windows disk management good enough that I uninstalled Diskeeper [another big drop in shut down time]
 
Switched to $69/year Office 365 subscription [Office 2013 dumbed down Outlook so much that it became useless as a To-Do list manager; I got tired of paying for upgrades every 3-4 years; the subscription is the less expensive option; MS are adding, and adding back, small, but important features that roll out monthly like SONAR; NOTE: I find Office 365 to be very stable on Win10, however, the Android apps, ESPECIALLY OneNote (which I uninstalled, and am switching to an annual $29 sub for Evernote), suck big time]
 
SONAR Platinum is very stable on my system