Anything you don't like about the 5X?
Like I said, my 5X is OK. I just find the 5.2" screen slightly too big to be comfortable. Oddly, my last mobile had a 5.0" screen, and that was OK to use single-handed, although barely. It was never ideal anyway, but I guess that 0.2" (roughly 5 mm) is enough to tip the scales from "just do-able" to "too big" for single-handed use.
In terms of usability, it's just not as good as my previous phones. My main usability reasons are:
1. A slight lag. Maybe this isn't typical of Android phones in general, but the 5X is a tiny bit laggy at everything it does. Even its responsiveness to touch has a lag -- something that only lasts for microseconds, but is there just the same. Even my friend's 6P is slightly laggy. Maybe the Windows Phone 8.1 world that I'm so used to is simply smoother?
2. The camera lag is infuriating. AF is slow, and when I press the on-screen shutter button, it can take 2-3 seconds for a photo to be taken. The camera app is even slow to call up! I have a 1 year old daughter that I photograph all the time, but I can't use this phone for photographing her whatsoever. That's not hyperbole. I mean that in a literal sense.
3. My wife's iPhone 5C, which is 2 years old and not particularly flashy, feels faster and more responsive than my brand new Nexus 5X, which is just unacceptable. My phone is NEW. Her phone was mid-tier when it was new in 2014.
My smartphone history looks like this:
Nokia XpressMusic 5800 (or something like that). Pretty good. Stopped working in 13 months though.
iPhone 3GS --- Good, not great.
Samsung Galaxy S2 -- Complete and utter dog-****.
Nokia Lumia 925 - BEST PHONE EVER! (except battery life). 4.5" screen was awesome, even with those wide side bezels.
Nokia Lumia 930 - SECOND BEST PHONE EVER! -- No
Glance, though.
Nokia 5X -- Not good enough.
Despite how it looks, I don't switch phones very often. I dropped and cracked my Nokia L925 (1.5 year old phone), and the 930 was stolen (after 1 year). This is the first time where I've felt compelled to take a financial loss just to get rid of a new toy.
The iPhone SE is my phone of choice right now. I'd love to get a 6S because I like the 4.7" screen more, but the SE is cheaper, and has a much longer battery life.