I’ve been using an iPhone 4S since the days when the iPhone 5 was the top-end model, so sometime in early 2013. That replaced an iPhone 3GS, which was the entry-level model when I got it in late 2010. And with iOS 9.2.1, the 4S has become remarkably sluggish.
OS X 10.9 Mavericks has just been released by Apple. Here are my initial impressions.