The major issues are that dodging, the downed state, and way point zerging (you can constantly run back from the way point, even on bosses) make it so anything that isn't a 1 shot mechanic is trivial to deal with so to keep the dungeons challenging everything is grossly over tuned. And even then if there isn't constant aoe to deal with then it's easy to bring someone up from the downed state.
Any aoe encounter becomes trivial due to the rally mechanic. Constant mob kills mean that even if you're dying a lot you just keep rallying. It's really wonky to go down, rally instantly only to go down again in a few seconds and rally instantly.
Just imagine WoW dungeons with no tank or healer, but everyone has a 2 second melee range res. It is challenging and doable... but not in a way that's fun or rewarding.