Prefer to order on the official way with the manufacturer.

Warning, this phone is in its international version at the manufacturer about its side (oneplus.net) available, if you have one of the rare invitations. The international version has a white cover for the 16GB version and the Sandstone Black Cover for the 64 GB version. In the original covers Cyanogenmod is noted among Chinese is missing regularly. The China version is shipped with the operating system coloros which by some dealers before reselling with Cyanogenmod 11S (= delivery Software International Version) is replaced.

The Chinaphone missing a few frequency bands. Info can be found here: [...]
Good overview of the general differences between the two versions: [...]

Prices from the manufacturer: Silk White 16GB. 269, - and Sandstone Black 64GB 299, - Euro each plus shipping (about 5-20 euros)

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For phone itself. I got lucky and Invite. Have the Sandstone Black (international version) with 64 GB of memory. The phone was advertised as a "flagship Killer", which at the price quite true.
Main features:
Processor: Snapdragon 801 quad-core 2.5GHz
Graphics: Adreno 330, 578MHz
RAM: 3 GB DDR3 LP, 1866MHz
Internal Memory: 16 GB, 64 GB depending on the model - can not be extended
Display: 5.5 "IPS Full HD with Corning Gorilla Glass 3
OS: CyanogenMod 11S - Based on Kitkat 4.4.2
Battery: LiPo battery with 3100 mAh
Cameras: 13 MP and 5 MP front camera haup
Worldwide frequencies:
GSM: 850, 900, 1800, 1900MHz
WCDMA: frequency bands: 1/2/4/5/8
LTE: frequency bands: 1/3/4/7/17/38/40
Dual Band Wi-Fi, Bluetooth, NFC
Exact specifications for your perusal: [...]

I come from a Huawei Honour and of course that is a Rießensprung. The phone is really fast and responds brilliantly. The 5.5 "are almost a little too big, but just in your pocket fit. Delivered it is with Cyanogenmod 11S, a version that XDA developed directly for the OnePlus One and repeatedly supplied with OTA updates. Android L is certainly promised . it is not rooted, but can probably be made very simple and one does not thereby lose the guarantee, as with other manufacturers often is the case.

In the small fee you should grab version definitely to 64GB, mainly because no SD slot is available. When a SIM MicroSIM is used, no DualSIM version.

Currently there is still a bit hard to get an invitation, but it is to be changed from Invitesystem booked in advance at the end of the year. Otherwise, just gaze times in OnePlus Forum since Invites are every now and then passed on. In addition, one finds a lot of information to your phone.

Generally, absolute purchasing know, as long as it is not the China version or the totally exaggerated prices at the middlemen. Buys directly from the manufacturer and everything is fine.