Have played using the new encounters... Was apparently really difficult to shuffle them into the new deck so my Stronghold access corridor was five challenges and a combat. Unfortunately (or fortunately) I got two of the multiplayer only challenges so my expedition was considerably easier than it might have been.
Just as well because the definitely non-sentient robot was the only one still standing coming out of Descent.
Planning to get the Ambull expansion and Escalation this winter, after or at least late in our craft show season, when we have the cash to hand. Not sold on Traitor Command, as yet. Let me know what you think once you see it at work.
So the Crusader is an absolute beast... fast, tanky as hell, and his aggro ability is wonderful (plus the Ultimatum's ability to manipulate the encounter deck).
The AdMech guy, well, I'm not so sure. His melee attack's stun is quite good if you're going up against a beast like the Ambull or Mallex as is his Designator, but his actual damage potential is pretty weak. His ship on the other hand is really, really good with its ability to flat out cancel an Exploration card. He's probably worth it for that alone.
As to the Ambull expansion: I haven't finished my first Ambull expedition yet, but my first combat encounter had the Ambull and Obsidius Mallex spawn within a few of hexes of each other and Mallex just got a bee in his bonnet about the blue Umber Hulk and tore him a new arsehole. Naturally the big bug wasn't pleased either so in the end the Ratlings were able to make quick work of the biggest, nastiest baddies I've seen in the game up 'til now. It's really been a bit too easy.
Really wish GW would make some unique aliens or factions. They started off great with UR025. Really thought they would use this to fill in the gaps and those not popular enough to be a 40k army factions.