I've completed two Honor Mode runs and the only thing I still haven't done is kill those two friggin Cambions in the tutorial fight. It's not too much more difficult than tactician, but the more restrictive action economy makes the round limit and increased HP more difficult to work through. Best I've done is get the last one down to 12 HP before the ship crashes.
The rest isn't much more difficult than Tactician though. A couple of Legendary Actions and the single save restriction are more of an annoyance than difficulty increase.
For builds: Thief Rogue 4/Swords Bard 6/Fighter 2(MC or Astarion), Eldritch Knight 11/War Cleric 1(Lae'zel) or Wildheart Barbarian 8/Thief Rogue 4(Karlach), Light Cleric 11/Tempest Sorcerer 1(Shadowheart), and Abjuration Wizard 10/White Draconic Sorcerer 1/Tempest Cleric 1(Gale) make really short work of everything from lvl 5-6 on. There are less than 10 encounters in the game that this party can't finish in 3 rounds at that point.