I decided not to comment too much on the epic until I had a good night's sleep. Since I finally slept last night, here's my opinion on the weapon. Feel free to share your thoughts too, I know there's a bit posted in the epic info thread, but I wanted to go more indepth. Please forgive me if I bore you to death.
Epic weapon pictures stolen from Duress:


(P.S. Grats, Raethe on your discovery)
My analysis will start with the basics, the stats and delay, and then move on the the individual effects. My overall take on the weapon is positive, but it doesn't mean that there's not problems with the weapon as well.
42 Sta, 32 Wis, 68 Int:
Stamina and int are great and in good amounts. But what's up with wis, and why do we always get it on our weapons? It doesn't do anything significant for us. Why couldn't we have had strength, which might help the minority but still significant amount of STR-line enchanters like this weapon?
134-401, 5.0 delay:
I'm sure this was standardized among all the mages, but this delay is really only above average. Since STR-line coercers exist, they actually get a downgrade on their melee dps in comparison to a Hammer of Swirling Constellations. It's clearly not a big deal, but it's something to chew on.
8 focus, 10 disruption:
Disruption is nice. However, there's a clear lack of other +skills, subjugation and ordination. Now, I know that our current hit rates are high so that testing the value of skills in raid isn't very important, but at least subjugation is the basis of the coercer class. Why not shove it on there instead of focus?
+5 Max Power:
Five percent maximum power is worthless. For someone with 10,000 power, that's a 500 bonus. Sprinted to volatile magic, that's 150 extra power. Really now, why not just give us more spell crit, spell damage, or if you were feeling generous, base damage. Essentially, I would have liked anything else. Maximum power is useless in the face of massive power regeneration and always will be, and we already have that regeneration capability, thus making this quite useless.
+8 Crit:
Pretty much makes this the best DPS weapon available for us.
Siren's Stare - Adds mental damage to fighter's taunts:
This ability is very good. Although it's group-only buff, it provides the fighter in your group an added 650 damage nuke onto their taunts. This is like giving your fighter Hemorrhage as well as Dissecting Gaze. Every 8 seconds, they have a 0.5 nuke for 650 damage? And the AE taunt, every 30 seconds. It has the potential to add 400-600 dps to your fighter. That will clearly aid your fighter in keeping hate, or just help dps in general. While your raid setup really determines the value of this spell, overall, it's a great ability.
Siren's Gift - 10% Reuse and 20% Group Power Reduction:
Ten percent base reuse is incredible. Currently, it's the highest amount you can get on any item, and only second in amount to the sorcerer's AGI line. DPS-wise you should see a boost nearly equal to the amount of reuse given. As a bonus, it also helps reuse on channel. I'm very glad about this.
Now, on the flip side, we have the 20% group power reduction. At the point in the game where you can obtain this weapon, power consumption is not a significant issue in raids, not only due to power regen abilities (especially those abilities of a coercer - base regen, Channel, Manaflow, Mana Shroud and more) and power-returning items (phantom piths and power-proc items and skills). If this ability didn't even exist on the epic, I wouldn't notice that I was missing it, and when it does proc, I don't notice that it's up. Overall, mediocre.
Siren's Flow - Group mana flow:
This is good. Mana flow now has a duration of 8 seconds between when we lose power and when we get it back, as well as half the cost in health and power. Futher, the group-target allows us to pretty much blast the raid with power. I use mana flow constantly, and while mana isn't a huge problem in raids, the abilty to totally control and replenish other groups pretty much allows others to go full out without worries about power.
The current problem is that it returns 10% power for every group member on termination. That's a 60% power return that coercers simply don't want. We have to sprint off enough of our power as it is. Hopefully this gets fixed or altered. It makes me wish they had given us something like the guardians which altered aa, so that our Volatile Magic line would no longer require a power amount. This would not only help adapt to the group mana flow but make us more viable when we channel and get ourselves to full power in that way.
Well, so there you have it. Highs and lows in this weapon; you can't say it's overpowered because most of the strengths lie in power regen (which is useful, but not vital), but you can't say it's crap either, because it offers us high utility and dps aside from the other abilities (with crit, reuse, and giving fighters damage to their taunts).