OnePlus One
Not much can be said that hasn't been said in most of the reviews. The phone is big. VERY big. I feel awkward holding it after getting used to my Nexus 5.
Screen- I don't seem to have any of the yellow banding that people have complained about. Overall it looks good so far. I can definitely tell there is some kind of difference moving from a 5" to 5.5" screen. My old man eyes still can't see the pixels, so for that, I don't see it as a huge "loss."
Physical build- It feels svelte. The arc to the back of the phone allows it to sit nicely in my hand, so I don't feel the corners as much as I do with the Nexus 5 or many of the other "phablet" phones out on the market. There is a nice balance between feeling substantial while not light and cheap, and the OPO hits that mark for me. I have the 64GB version, with the "Sandstone Black" case. The only way to describe it to me is that it feels like a very short felt. It is indeed plastic, but it has a texture that keeps it from feeling like it will slide from my hands.
I will say that I'm incredibly displeased with the single color charging/notification LED and navigation buttons on the device. They feel like a complete afterthought, and I'm glad that I can turn off the nav buttons during setup. The extra chin area on the bottom is a bit of a bother to me, but it isn't a game-breaker.
I realize this is a small complaint, but I've really grown accustomed to Qi charging in my devices. I have chargers around my house and on my desk at work. Unfortunately they're going to be mostly useless now, except for charging my N7. I'm a huge fan of not putting undue wear and tear on USB ports, and this has been by far the thing I'm going to miss the most while moving from my N5.
Software- If you've used CM in the past, you're going to be at home with the OPO. I absolutely wouldn't buy this phone for a user who is new to Android or smartphones. There are too many features (nav button modifications, theme engine, status bar mods) for someone to use it who hasn't tinkered with the phone before. I don't see this being a huge "oops I bought the wrong phone" considering the invite system.
CM11S feels smooth. Damn smooth. I can't speak to how it will be in the long run after I get everything running for a few weeks, but for the time being, it feels incredible coming from a Nexus 5, which is absolutely no slouch. I felt like I needed to turn off some of the features like the quick settings ribbon on the regular status bar shade, and a few other small additional options, but in a lot of ways I really enjoy a very vanilla Android experience, and the OPO gives me that with a bit of tweaking.
It paired up quickly and easily with my Gear Live device, and so far BT connectivity has been on par with my Nexus 5. I can go downstairs and I don't lose connectivity with my watch, and reloading all of my apps (watchfaces, launcher, etc) is quick and smooth.
Overall-Even though I have a few complaints about the device, I like it. We'll see over the next several days if I can deal with such a large device. I plan on giving it at least a week of real-world use, and I'll have to report back after that.
If anyone has any questions about it, feel free to let me know. I'm working from home the next few days, so I should have time here and there to be around this thread.