So my group played through this last night. We had very little trouble with most of the encounters, but that was more to do with our party composition than any basis in the encounters.
Goblin Wizard with crowd control spells
Human Wizard with melee specialization
Dwarf Barbarian
Human Cleric
Human Fighter with a shield
The first fight with the slime, and then the following fight with the goblins were both fairly easily cleared with front to back battle lines and some smart crowd control.
The encounter with the centipedes... was not. The cramped quarters meant that lines of sight were impossible for the wizards, so the front line got swarmed, and that's where we found out about the high lethality of the adventure packet.
The centipedes had an average hit rate of just around 65%, which, combined with the poison, meant that most of the party was poisoned and near 0 HP at some point. (3 or less HP, for reference.)
The goblin ambush in the room with the fire, in comparison, was easy...
Because the goblin wizard cast Sleep on half the ambush before combat rolls.
Similarly, the encounter with the Faceless Stalker was easy because both wizards had Magic Missile prepared; 6d4+6 damage is not to be scoffed at, at such a low level.
So yes, party composition and spell selection carried the day by outright negating most of the encounters.
That being said, my thoughts on the edition are fairly straightforward.
1st thought: The monsters being able to out-stat players of the same level isn't necessarily a bad idea, if the monster in question is meant to be huge and intimidating. When a basic Goblin does, though, is when it turns into a problem. Goblins should be scary because of numbers, not because one goblin deals an average of 7 damage in a round. And that's just one example.
2nd thought: The skill system is a mess. I can see what's being attempted, but it punishes anyone who wants to pick up a bunch of different skills by minimizing skill progression and locking the most interesting flavors behind Signature Skills. Simultaneously, it also reduces the feeling of "I am actually advancing in skill" because everyone gets a base +1 to all skills every level, which the monsters also get. It just feels like a case of 'bigger numbers for the sake of bigger numbers' because, statistically, everything remains roughly the same. Literally could do away with the redundant +1/level entirely, and instead unlock level related effects like spell level as the player reaches the appropriate level. It'd feel less like number bloat.
3rd thought: The 3 actions per round felt sleek and interesting, and it's different in an exciting way. I actually enjoyed it alot, especially because it adds a different dimension to tactical thinking beyond the standard "move and attack or full attack?"
Edit: Also the Shield rules caused a lot of confusion, such as in regards to the Centipede poison, and the Denting rules.