iOS 9 - Should you upgrade?

With fall (and September) comes the new Apple stuff, and of course, for those of you staying with your existing equipment, the new Operating System.  I have been testing iOS 9 for several months now, and I think there are some very compelling reasons you will want to upgrade:

1. Security - As NPR reported, IT experts all agree the number 1 method to ensuring computer security, is to apply OS updates as soon as they come out.  You need to stay ahead of hackers, and this is the best and easiest way to do it.  NEVER forget, your "phone" or tablet is a full-fledged, desktop-class computer.
2. Low Battery - one great feature of iOS 9, is that if your battery gets low, it switches to low power mode.  In this, it turns off all the non-essential parts of your device, so that it lasts longer.
3. Low Memory - iOS updates take room to download and install, and on devices with smaller memory, you may not have had enough to update.  The remedy until now has been to download on a computer with iTunes.  But now, iOS 9 will determine which apps it can delete to make space, delete them, and restore them once the update is done.
4. WiFi Calling - to me, this is a GREAT feature (for those of us not on T-Mobile).  AT&T added me to their WiFi beta testing program, and working in areas where I get a low cell signal, but have great WiFi - I have been able to stay on phone calls with absolutely perfect clarity and no dropped calls.  This is awesome.  The phone automatically switches as it becomes necessary.  The one caveat in the agreement to turn on WiFi calling, is that they cannot use location information for enhanced 911 location.  So you have to register an address when you turn on WiFi calling, and you can change it at any time, that will be sent to 911 if you place a call on WiFi.
5. Frequent Contacts - before iOS 9, you access frequent contacts (as an option) at the top of the app switcher screen.  With the redesign of app switcher, they moved it to the "swipe right" from home screen.  And, it only shows the last 4 to 8 contacts.  To me, this was a big beef.  I personally asked them to restore the contacts on the app switcher screen as an option, but so far they have vetoed the request.  If it makes it to Live in this manner, and you were used to using the contacts feature, you will (like me) have to get used to going to Home, swiping right, and only getting the last few on the screen.  Not as intuitive, not as accessible.
6. Better Battery Life - at the June 2014 WWDC (Worldwide Developer Conference), Apple introduced Metal, a new "lower-level" closer-to-the-chip graphics programming engine.  Designed to replace OpenGL (which is cross-platform, and not optimized for the Apple OS and hardware), it allows, for example, game developers to write games that take full advantage of the graphics hardware, and do it in the most efficient way possible.  That was iOS 8.  In iOS 9, Apple has rewritten their Core Graphics libraries, upon which all apps (and all of iOS) are built, using Metal.  This means that, after your upgrade, your device will run faster, and use less battery power for the same tasks.  As an aside, I have been really enjoying the introduction of Metal to OS X (the Mac OS) this year in El Capitan, where it has made my 6-year-old laptop run even faster, and the battery last even longer.
7. Faster - even on older devices, the Metal rework has made the entire OS faster.  You would think you wouldn't notice it on a 64-bit iPhone 6, but it was noticeable even on that platform.
8. Very stable - I have been an iOS Beta tester for 4 years now, and this release has been extremely stable.  In fact, only in the first couple of releases did it crash, and then only at night while I was sleeping.  I knew because when I used TouchID to unlock it, it asked for my passcode.

Now, there are many other enhancements, including more capabilities with Siri - but I'd say those are the top big things you will notice.  Many under-the-hood changes are for developers, and will accelerate the capabilities of apps, so you will see newer kinds and better apps come out soon.