Not necessarily bad, but like a weaker version of the adept or a significantly weaker engineer. But I personally found the class to be really annoying early on. They'll burst your tech armor which will make them stagger or fall over, and you just finish them off, put your tech armor back on, and move on to the next target. You can basically just walk up to any enemy and 1v1 shotgun-to-the-face. Sentinel gets VERY easy near the end of the game with Assault Armor and your passives leveled up. Adrenal Rush or Tactical Cloak help you stay alive while killing enemies faster. Soldier/Infiltrator are just really solid choices and should be pretty easy because weapons are extremely strong in 2 compared to the other games. I've only played 4 of the classes on Insanity in ME2 but these are my opinions: I've seen lists that put almost all of the classes as the easiest depending on which ones the person liked more.
