OP, welcome to FlyerTalk
You'll find we have a fair amount of Global Services members here. Very interesting and diverse group.
Often (but not always), they identify themselves in their program area (like where you put your 1P status); some will simply put GS or UGS, or they might put their level, like GK (like RobotDoctor) or GP. These signify mileage flown, similar to 2P, 1P and 1K. Hence, a GK is a UGS member who has flown at least 100K EQM's in the last qualification period. I believe any UGS member will be identified as GP (the 50K EQM) at the minimum, if they haven't flown to the 100K level.
From my readings, the main benefits are more individualized service, more flexibility to accomodate a UGS for changes/upgrades/awards/irrops, etc., as well as the more obvious things noted in GA/FA announcements and UA signage around airports.
As a 1P, you enjoy many elite benefits not afforded to most casual passengers. Enjoy the ride and your stay on FT
Pat