If you are talking about the ios 8 BETA since the real version isn't really out to the public yet. Here is my experience with it hands on... When I was doing the testing for it on my iPhone 5c I noticed that it was slow at first but after having it run on my phone for a few days I noticed that my battery life had increased but my phone was starting to hiccup/glitch pretty bad, Keep in mind it's just a BETA version so it will have a few problems. But all in all it was a great experience and I even found a lot of new features that I love about the ios 8 but I DO NOT recommend you download it from any website! It's better to wait until it becomes available to the public.
I hoped this answered your question.
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