I dont think the general consensus is " Shut up Noob " and if I gave that impression I sincerely apoligize. Many of us have been playing from early on when Sentinels were in a very bad place. They have gotten MUCH better. Sentinels have just as much value than any other AT in the game even if it doesnt excel at ONE specific thing.. and that in all honesty is the beauty of CoH is that everyone is viable..
Here is how I see the Vulnerability and I think it bears repeating..
Vulnerability is Auto-Hit and ignores level differences.
Vulnerability debuffs the following:
Damage Resistance
Defense
Mez Resistance
Stealth
Resistance to Endurance, Endurance Discount, Recovery, Regeneration, ToHit, and Recharge.
The fact that ONE power does so much and it is AUTO hit and works the same if you are fighting something your level of +4 is actually really really good.
And one thing that Vulnerability does do which I dont think many people understand is that it makes other characters debuffs work better.. It enhances anyone elses -regen,-end,-to hit,-recharge powers. Anyone on the team that has powers that do any of those.. makes them work better simply because an auto hit power that CANT be resisted.
It really is an incredibly good power.. for free..