My group had only started the Caves of Chaos when the second playtest hit, so we elected to carry on with that adventure by updating the characters win the new character creation rules and using the new bestiary.
We found that along about 3rd level, the rogue could break the game for everyone else with his damage output. It was just too easy for him to gain advantage and annihilate the enemy. Everyone else felt obsolete, except the fighter who's only job was "stand there and flank so the rogue can sneak attack."
Even the guy playing the rogue was rolling his eyes at how his character was mopping up the battlefield.
Mind you, that may be because the caves are designed with a OD&D mindset that predates the modern form of sneak attack.
It may also have been the fact that the rogue was a halfling and once we got past the goblins and kobolds, he could maneuver at will through enemy spaces to get flanking advantage very easily.
Me and the other guy who trade off DMing have been discussing nerfing the damage progression of sneak attack until we get the next playtest update, just to keep things balanced.
We start Blingdenstone next session. Maybe it will be different.