DPS training mission are ok, they could have done some AoE training but that is minor thing. Granted I ran as a Ninja and the trials might be a little different for a range DPS.
Healer training missions have three major flaws.
1. The NPCs are not a member of your party.
Pets heals from Eos or Selene do not heal them.
AoE heals do not heal them. No AoE heal training at all.
Also, as they were not a party of the party, I had constantly re-sheath my weapon due to my target cycling filters. This issue generally only affects game pad users like myself.
2. No combat resurrections/raise/ascend
3. No stance dancing training.
Tank training missions are decent but I have two minor complaints.
1. they do nothing how properly regain Aggro by using Provoke.
2. They do nothing about tank positioning of targets for DPS and group AoE dodging.