The latest Grim Dawn expansion didn't fix everything that bothered me about the action RPG; I still don't like how skills and masteries synergize with each other and the two new classes - Necromancer and Inquisitor - don't fix that much. They add some interesting mechanics to the game, but otherwise it still feels like a slog to play. I managed to get through the new story content, but I'm not chomping at the bits to go back to more Grim Dawn.
The two new classes aren't that great because they continue what I dislike about classes in GD and they focus too much on active skills that seem to overlap in utility. It's nice to have damage dealing skills, but having a bunch of them that sound alike doesn't make for more fun gameplay. The inquisitor class can dual-wield pistols and use some spell-like damage abilities while the necromancer has an army of minions with them. After trying them both I went with the necromancer since at least your summons were more or less overpowered and could destroy everything in sight while the inquisitor just went 'pew pew pew' forever.
Otherwise the game hasn't changed much. It's not like Diablo 3 where the first big expansion brought us Adventure Mode and much needed legendary item changes, this feels like a minor update to the game and I'm not sure if Grim Dawn can get to a point where I'd be more interested in playing it. I'm also not a fan of the lady they use on their loading screen.