iOS 9.3 worth updating or stick with current iOS?

I have an iPhone 5s, the Tapatalk app has been acting up for no reason, literally opening it up and once into a forum it crashes. Tech support suggests updating to the latest version, in order to do so I will need to update to the newest OS, or at least 8.0

I currently run 7.1.2

I'm concerned that updating my OS may result in my model phone running more slowly as this sort of behavior has been reported with other OS's and previous iPhones. I don't want to udpate my OS for an app if I cannot use my phone etc.

My questions are

1. What's the best way to back up my phone so after updating if it runs slow etc, I can restore my phone back to the current iOS I have now and all my data back onto the phone ??

2. Is it worth updating to the newer OS or have people seen problems?

I have no idea why this App is not working anymore, I haven't added anything onto my phone.

I get the impression iPhones are only good for about 2 years and then they start acting up.

via iLounge Forums http://ift.tt/24Rkaej