Leveling is fast here, a druid as it is, is perfectly capable as a 2nd box healer to get to 51, after 51 yes they could use some work.
They have a damage shield, regen / chloroplast, sow, decent heals leveling, decent dots, root, beast charm ( used the heck out of it in jagged pine) snare, HP buffs, ports etc, getting there isn't a issue, I did it with a druid box duo easily, and other have to.
I'm not for giving them a slow, and cleric's shouldn't have the undead slow either imo. They should have their dot damage increased, big heal increased, a lesser heal over time than cleric's ( but at least a decent HoT). Maybe give them a second 4 per tick self only mana regen spell that stacks with everything. Or a reverse damage shield like the cleric used to have ( mob attacking does damage to itself when it attacks ).