Tykens rift drains energy from enemies close to it (2km radius, at least at lvlI). It is highly dependant on your aux level and lasts for 8 seconds.
It can be quite brutal (with the skills and especially aux-power) in PvP, disabling shields at this weapon junkies, stopping them because their engines run on 25 too and decrease their damage.
It's nice to watch in PvE
In PvE I find that it is quite useful when with friends/in a coordinated group. The rank II ability with max aux and some science consoles when combined with target:shields will drop the enemy's shields for a good 5 seconds--enough to take out a battleship without touching the shields if a friend and I hit it with quantum torpedo volleys. I can imagine it will only get nastier as I get higher in ability.
It also makes the enemies more sluggish and hit less hard with their beam weapons, which is always a plus. It's only spectacularly effective for a coordinated opening assault in PvE, during the fight it's just gravy.