When the iPhone 6 first arrived in September, we and many others encountered various bugs and issues. Many of these problems stuck around up until the iOS 8.3 release earlier this year.
iOS 8.3 rolled out with new emoji keyboard but it also delivered an extensive list of bug fixes that shored up most of the lingering problems on the iPhone 6. Wi-Fi has improved and we no longer get stuck in landscape mode.
iOS software is never going to be perfect, just like Android and Windows Phone aren't perfect. That said, iOS 8.4 is the most stable version of iOS 8 that we've used and with iOS 9 focused on improving performance, we're confident that the iOS experience on the iPhone 6 is only going to get better.