The biggest difference to Android is basically the start screen - the tiles. They're used to, but can be adapted very easily to his own taste.
Apps referring, of course, not on the Google Play goals, but on Microsoft. And yes, the choice is there less, but that does not bother me in the least. What I wanted, I've found.
What I like the Lumia 830: It is really a powerful smartphone that puts great emphasis on office functions and a (for the price) very good camera with optical image stabilization has.
My decision for the Windows Phone I've taken to get my contacts from the old Nokia C6 easier anew cell phone. However, there are a few things to note:
The Lumia provides for a convenient "data transfer" via Blutooth. An ingenious thing. Unfortunately it does not work with any old phone. My C6 has refused.
ATTENTION: The Lumia 830 can not be synchronized with the Nokia Suite! I had my data backed up from the C6 with the Nokia Suite. In order to get them on the Lumia, one must however having to go through Microsoft's cloud SkyDrive / OneDrive.
The latest version of Nokia Suite offers directly to help to transfer the data to SkyDrive / OneDrive. Then you have to practically only login from the Lumia on OneDrive and you get its data (contacts, calendar, photos, music).
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Addendum:
In order for the alarm clock works, the phone must be turned ON.
All my previous phones could be switched off. When the alarm went off, it was asked at the same time if the phone should be switched on.
However, the Lumia Do not turn off. Anyone who wants to protect nevertheless undesired calls or against cell phone waves directly on the dessert beside him, who can simply activate airplane mode.