In comparison with published short term iOS 8.0.1 , the current version is stable, but still away from perfection on an unpleasant bug told by MacRumors. According to their report, resetting all the settings in the “Reset” erases the data from iCloud Drive, which does not provide for recovery in the future.
In the settings menu “Reset” offers several options for data cleaning. The topmost button “Reset All Settings”, in contrast to the “Erase All Content and Settings”, does not imply the removal of user data. However, according to the source, if you are using a suite of applications iWork and your applications store documents in iCloud, the data may be lost.
Till today, no information confirming the loss of any other data on reset, and the error is unlikely to hurt those who do not use iWork. However, if you are among the users of office suite applications from Apple, advised to avoid doing resetting.