I wiki'd the gun, and I got this:
Will teleport you between the Mojave Wasteland (Mojave Drive-in) and the Big Empty (Sink balcony), whenever you want as long as you are not in combat, in an interior or in The Strip, Freeside, Hoover Dam or The Fort. This is especially handy if you've made The Sink your base of operations and need to get there fast.
Despite technically meeting the outdoor criteria needed to use the Big Mountain Transportalponder!, some areas will still not allow travel (via the weapon). Examples of this include the The Strip, Freeside and Hoover Dam.
The Transportalponder cannot be used to travel from Zion Valley to Big MT, nor from the Sierra Madre to Big MT.
Transportation is possible while overencumbered.
Since the Transportalponder isn't technically a weapon, it can't be used in V.A.T.S.
The Transportalponder is regarded as an essential quest item and therefore cannot be dropped.
Since the Transportalponder is a quest item, it will not be removed from your inventory by any means, such as legion slave duels, or undertaking Dead Money.
The Transportalponder cannot be used during combat.
The Transportalponder can be used while falling.
The blue and orange motif may be a reference to Valve's hit logic game Portal, in which a pair of portals are blue and orange. This is fitting for the name of the device.
I hope that answers everything you have about the gun! It sure did answer mine.