Oneplus one

Oneplus one, 1+1.

My experience so far:
Very buggy software, lag, stuttering, freezes, hickups and random reboots. This was on cm11s 33r.
I've tried a lot of different roms and kernels. All are buggy, some more, some less.
They all score insanely high on Antutu benchmarks. That's not the same as having a smooth experience in daily use..
The cool thing is that the is so much development going on, so many different roms. Bugs will be fixed sooner or later.

Camera.
I'm impressed with the video recording. And macros.
Other than that, meh.
Pictures come out blurry, and color reproduction is lacking, photos look washed out. A lot of noise. HDR mode is worthless.
I have not tried the ColorOS, I've heard the camera is better with that software.
Yeah, I guess it's not the sensor that is bad...
I used to take a lot of photos, but this device... It's just not fun anymore.
Good selfies though.

The screen,
5.5" is nice, and the screen is great.
Very bright and sharp.
A frozen pixel appeared after only a few hours of usage, I didn't bother to return my device, customer support is... Well, are there any?
Pixel still frozen, red. Tried many fix apps...

Battery is great,
I was used to charge 3 times a day, now I have battery all day, sometimes 2 days.
Really really great battery.

Speakers.
Placed at the bottom, when gaming in landscape mode speakers are covered. And that's crap.
Sound quality is crap, and the speakers being loud only makes it worse.
Though, the speakers are pretty good for voice. Loud and clear in speaker calls, video calls..

Capacitive buttons,
yeah I love those.
I really do hate on screen navbar, it's the worst thing that ever happend to Android.

64GB internal storage. 3GB RAM. Brilliant.

Signal,reception.
Very buggy, very unstable.
Have no 4g in my area, only gsm and 3g. Terrible on 3g, good on 2g.

So, to wrap it up, for it's price it's a good device. Eventually the experience will be better, when bugs are fixed. I would not label this device a "flagship" Definitely not a flagship-killer.

Update: CM11S 38R, after this update, the user experience is noticeably better, smoother. I've only had one random reboot, during video playback in the gallery app. (That has happened before, yes..)
Still, my Xperia ultra opens apps faster, and lags less when playing games.
GPS lock is still slow, even if I modify gps.conf.
3g data is still not good.