iOS 6 was better because the look was more consistent and less eye-searing, but I still didn't love the design. Personally, I don't find skeumorphism to be preferable on mobile to intuitive (which it isn't always) clean and flat design. Skeumorphism is good for transitioning users over to a new and unfamiliar ecosystem because analogues can make it easier for them, but on smaller screens you want clarity and consistency. Removing drop shadows, though, didn't actually help, it made text harder to read. Glass reflections and translucency/transparency I don't really care for from either the old or new iOS design language.
By the way, does iOS still (as of 9.2) not have a way to change the theme to dark without jailbreak? Searches only turned up high contrast in accessibility. I'd also love a Twilight or f.lux type of app. I hope Google, Microsoft, and Apple start baking better night mode features into the design of their OS'.
I don't hate iOS as a whole anymore because it's usable and fast on the latest Apple hardware, but I'm not a fan of the UI/UX design. For all the credit people give Apple for being great at design, it's not the UI design that they excel at, it's the physical design and hardware (and maybe how the software interacts with the hardware at a lower level) that is harder to find fault with. iOS was never pretty (except for the brief time where it was head-to-head against Windows Mobile, which isn't saying much since it also lacked basic functionality at that point), and Mac OS hasn't been noteworthy for at least 6 years.
I keep getting iOS devices every so often (in order I've had an iPad 1, iPad Mini 3, and 6th gen iPod Touch) and play around with other people's iPhones whenever a new gen comes out, but I'm still not a fan. The hardware is really solid, though, and I like how their devices feel. Superb aluminum bodies that are worthy of imitating (and the industry has). One of these days I probably will get a current gen iPhone, jailbreak it, and be happy with it... it's really only the limited customization options that Apple gives you stock that has stopped me in the past, but researching what you can do with jailbreak has made me much more interested.