Greetings!  I am a new P3P owner, and have flown only a few times so far.  My initial flights were indoors without GPS, so a little tricky for a newbie.  I discovered the need for prop guards right away, and I purchased some but have not yet installed them.  I was wondering how they affect stability, maneuverability, and battery life.  Thanks.  

it doest affect in the stability or the flight time , may be the phantom is a little bit slower in windy days ,
but i prefer to fly without prop guards

On some projects clients request them for indoor flights.There is a marginal flight time reduction more so if used outside this also applies to stability.If you decide to use guards stick to genuine dji approved only.The main problem in the use of prop guards is their appearance in your camera view and subsequent video,this can be controlled some what by lowering the camera a few degrees and subtle rc control inputs.ONE OTHER POINT IMPORTANT when fitting prop guards it will be necessary to use a longer screw which will be supplied with the dji product when removing the guards make sure to fit the shorter screws or you will WARNING DAMAGE THE MOTORS