Flying in attitude mode vs.GPS mode sort of depends on what you want to do and how long you have been flying. If you are a new flyer, then GPS can be your friend. If you have some time on the sticks and want smoother steadier video then you may find attitude mode a bit more useful.
When flying in GPS mode you have position hold within about a 3 foot diameter. If you let go of the sticks, the copter will stop and hold position. This is helpful if you lose track of your copter and a need a second to get oriented. GPS is also great for windy days when you need extra stability or want to hover in one position. Keep in mind that this is all predicated on a having a satellite signal. If you should lose signal GPS mode could give you false position information and on occasion things can go wrong. You will not have the control of the copter that you think you have. Most pilots will tell you that the sooner you become comfortable with ATTI mode the better.
When you are flying for cinematic purposes you will want to fly in attitude mode. In ATTI mode if you release the sticks the copter will continue to glide in the direction it is pointed for some distance and a corrective stick movement will be required to bring it to a stop. This can be really helpful when trying to get a smooth tracking shot, but keep your eye on any obstacles that your copter may collide with. To really get smooth footage, practice flying in ATTI mode. It is also best to take off in ATTI mode as finding out that you lost GPS when taking off doesn’t allow you much time to make any crucial corrections.
We hope that this gives you a better understanding of the two principle modes of multi-rotor flight. Enjoy and fly safely!