First flight of Iris+, tumbled over on take-off, worked it out was trims not balanced (was trying to fly backwards), compensated at take-off but even will full trim forward still need stick forward as well. Thought might be due to weight so fixed GoPro to standard mount (non gimbal) and made no difference. Any suggestions appreciated.
It does sound like you some setting is not right on your IRIS+, if you say you need to have the stick forward just to get your quadcopter to fly level then the first suggestion I have is to go through the initial calibration again as I think the sensor level calibration is off.
The video below shows you how to complete the level (calibrate accelerometer) setup
Hope that helps