Hiya,
Like you, I'm not great with reaction time and I can stand in fire. My video game background is as a healer in Warcraft where I stand at range and avoid danger. With that said, this game is a hoot and I can't stop playing it. The reason is that you will die frequenlty, accidentally, shockedly and hilariously. You may defeat a hard boss and then fall to some dogs you did not expect and are not equipped for.
The reason it's fun is that there is not much penalty for death. You keep any gear you grab before dieing so suicide runs are effective. You do not pay repair cost, in fact, you revive repaired. You may lose your souls currency but you have a chance of grabbing it back and you can always keep little cash on hand by frequent upgrades or purchases.
In all, you want to play this game.