The alien blaster is one of the most powerful weapons in the game because a critical hit is guaranteed. You will often be able to take down any foe you encounter with one well-aimed shot to the head.
This weapon also has the effect of disintegrating any enemy killed with a critical shot by it (which is every shot for creatures weaker than most super mutants), identical to a laser (with the exception that the disintegration effect is colored blue instead of red).
Dogmeat can be used to recover the blaster from the crash site if you don't want to start the Mothership Zeta add-on, but still want to have it.
The neon glow turns off when the player enters sneak mode.
On Mothership Zeta none of the aliens make use of this weapon besides the captain (which is a unique version).
If you have the add-on Mothership Zeta while trying to take the Alien Blaster, you will be sucked up into the mothership. You can not get the Alien Blaster until you complete the add-on.
The shots fired from the Alien Blaster have been known to actually follow the target in V.A.T.S. if you miss. For example: if you go to Deathclaw Sanctuary, the Deathclaw that guards the entrance might randomly start flying up in the air. If you target it in V.A.T.S. while it's still on the ground the shot fired might follow the Deathclaw up into the sky when it starts flying.