I have faithfully been taking two 600 mg tablets of cinnamon morning and night (2400 mg/day) for a little over a week now.
On 10/11 my blood pressure was 114/66. It is about the same now. So far, then, no big blood pressure change.
The other measure that may be affected by cinnamon is the cholesterol. I will have it tested in a couple of months, trying to keep most everything else the same, and we'll see what happens. I have my new blood pressure medicine (Zocor), but haven't started taking it yet.