I have had many problems with Reminders in iOS 7 (just updated to 7.1.1). My Calendar items synch perfectly to Outlook -- no problems at all there. Reminders are another matter. At first, when I created tasks in the iCloud folder in Outlook, the tasks disappeared from Outlook, but appeared on the iPhone shortly. However, just about everything except the subject was changed -- wrong reminder time, not recurring, wrong emphasis, etc. Then a few days later, they reappeared in the Outlook folder, but some had peculiar characters in front of their names --something inside a dotted rectangle.
Leaving aside synching problems, on the iPhone itself Reminders have numerous problems. All the Reminders I have made are recurring, and every day or so one or another of them reverts to a single-date Reminder, so I have to keep making them recurring again. They occasionally switch to the !!! emphasis, even though they are set up with no emphasis or just one !, and the reminder time occasionally switches to 12:00 AM. They are hardly worth maintaining in this state, but I will keep using them for a while, just to document all the problems.