I had no problems installing it on galaxy s3 and note 4. Only thing to remember is kill DJI GO process in a background before starting Litchi app.
It offers much more then DJI GO. You can create autonomous missions on your PC or phone/tablet and upload to your drone. GO also has this option but the big difference is you must fly to every waypoint before starting a mission.
It has focus function which is useful to me. Point an object on a map and your camera and gimbal will automatically be controlled and faced to the marked point.
Visual track mode will track you using image recognition. However it need to be improved (in my experience). It tracks only 10 meters and loose target.
I have more stable signal and increased range using Litchi (not much, maybe 10-15% range extended).
Personally, I use only Litchi. However, I would not recommend this app for beginners. You should know all drone issues with GO first.