I have yet to try a Soldier. The armor/weapons just pale in comparison to the powers of both Techs and Biotics (especially in 2). My preferred class is straight up Biotic but mostly because that's what my ME1 character was when I beat the game.
I would play classes like Adepts more if it was more useful. The Shield/armour/barriar sort of screws non combat classes up. BEcause the moment you get to health, unless you're playing insanity, I may as well just gun down the health
Though atleast they made the infiltraitor and Soldier more then ME1. Though infiltrators can make the game too easy. I bet the two bosses in lair of the shadow broker would of given me more trouble if I did not have tactical cloak.