This is day 6 with my iPhone 6 after I moved from my HTC One M7 Android device. Well, tl;dr: I am happy with it. It just works. It's still fast and stable. One thing I want to mention in this post is the battery life. My phone worked for 2 days and it had left 30% of battery due to using all the social networks, Whatsapp, mail, gaming and watching some videos. We just watched the Apple event this evening and I also saw some minutes on the phone with 3G- fluently. On my PC though I wasn't able to watch it via Chrome or Firefox. At least I managed to see it on Windows 10 with Microsoft Edge. I think this browser was not detected to be "unworthy" or - if you allow me that sarcastic statement - this is the browser Apple allows since Microsoft had it's own part on the presentation. Steve Jobs would resurrect if he would have been seeing this.
Anyway, even on low battery the phone performs very well. I just had problems to charge it as I used the original cable on my Anker multi-charger and not with the shipped plug. After a restart it worked as intended with the Anker device (which provides 2A instead of 1A).