Very Good I have used this several times on transatlantic flights with GPS switched on. It accurately reports ground speed, heading, and GPS altitude but not pressure altitude. The attitude indicator is a little oversensitive and needs damping options, likewise the rate of climb. Ability to set the pressure QNH / QFE would be good for unpressurised a/c. Perhaps compensation for cabin altitude could be added for pressurised a/c so we would get correct flight levels. The IAS reported is actually the ground speed.
Needs a few more features Only tested on the ground so far. The artificial horizon can be calibrated by pressing the ATT CAL button, ignore the reviews that say otherwise. To make this five stars it needs more configuration options such as adjusting sensor sensitivity and not displaying sensors the device lacks such as pressure. I've tried nearly every app similar to this, very few compare.
Not useful in flight... Update - unusable in the air. It seems that vibration completely wipes out the gyros for my smartphone. Trying it while holding it in my hand to isolate the vibration, it still does not track the horizon like an aircraft gyro. Works flawlessly on my Note 4, on the ground.
Good but could use improvement Works as well as your hardware with acceptable accuracy. Could use a calibration option. Orientation on my hardwares mount is not perfectly level and thus pitch is always 20° off. being able to "zero" at least the pitch would be much better.
About Attitude option (altimeter) I recommend you to add the attitude value option that can change from gps to pressure sensor. I would be nice if you can add this option. One thing this app should allow user to select about the rotation. The rest are donw very well.
Bad value Bought it thinking that it would help teach the system. It's just a compass. Save your money. Wish someone had mentioned this before I wasted $5.
Pitch and roll accuracy enhaced.
Compatibility with more devices.