First off, I never tried Sentinel.
But just seeing how you guys (I'm a BH myself) have so much trouble with one elite tells me it's quite a hard class to play right, since you seem to do mediocre damage and have low survivability.
As a BH I can easily solo 2+ elites, I have a ton of AoE that takes mobs down in 2 seconds, high single damage abilities that destroy elites in under 20 seconds. If I pull aggro I have my heavy armor and heals. And I do a ton of damage in warzones, just did over 200k on my FIRST warzone yesterday as a lvl 18 bounty hunter.
So my advice, either try another class or wait for BW to change it. Honestly, I doubt it will stay this way.
I also believe most of the bad impressions of the class come from the fact that they have seen what other classes are capable of.