Seems more like a Calendar than a To-Do List
I guess it is true to its name, "Reminders." That seems to be what it was built for, from what I am seeing. I was so surprised to see that I could not enter a Due Date when creating a new Reminder on my iOS5 device. Only the "Remind Me" field is available for setting a date. This is different than Due Date as it pops up an alarm - like an iCal event. That is the last thing I want when I have 20 To-Do items for the day.
However, all my tasks sync perfectly with our Exchange server, and all the Due Dates that I have entered in Outlook do show up perfectly in "Reminders."
Hopefully, this is something Apple will tweak in future releases.
Note: I have not signed up for iCloud yet due to some compatibility issues. I don't know if this would have any affect on the problem. From the post of Nikhil72, it seems to be a problem with iCloud users too.