I've had an ongoing flirtation with the OnePlus One. The first one I traded. The second one I sold. The third one I kept and used.
It really is BIG.
I got used to the size but the niggling issues drove me crazy.
The compass didn't work after upgrading to Lollipop. Seems to be a common problem with Lollipop but my Moto X doesn't have the problem.
Cyanogen OS 12.1 replaced a couple of the AOSP applications. The most irritating one was the inclusion of TrueCaller. Let's just say the the OnePlus community didn't have the same perspective as OnePlus. You could opt out of the sharing capabilities of TrueCaller but my beef was that TrueCaller's incoming call screen had a small thumbnail of the caller while the AOSP had a full screen image.
The vibration of the OnePlus One was very weak. So much that I pretty much couldn't feel the vibrations with the OnePlus One in its holster on my hip. Subsequently I turned on audible notifications for everything which is irritating for everyone.
When I was talking on the phone people mentioned that they couldn't hear me clearly. Some Googling turned up that "Ok Google" detection causes problems with voice during calls. Turning off "Ok Google" detection "fixed" it.
The screen's brightness kept lowering resulting in the screen being pretty much dark when you received an incoming call. I tried several of the workarounds to no avail.
And the battery, while longer lasting than the Moto X, still wasn't as good as my wife's iPhone.
So I listed it on swappa and it sold the first day. Obviously I didn't ask enough for it.
What's next? RDF