These are my first games ever with Adventures Cards, so I'm avoiding playing Rated games until I've got a handle on most of these cards. I've played a bunch of games with a friend of mine, but have also been playing through the campaigns.
The campaigns are a pretty good way to learn about the cards and to figure out how certain cards might fit into an engine, when to use Card A and to avoid Card B, and when the opposite is true. However: as advertised, the AI in the campaigns is not very good. For all the other expansions, the AI would be really easy the first few levels, but then would at least become challenging once you've hit the 9th or 10th stage of each Act. Not so in Adventures. I've yet to have the AI opponent push me at all; at least in the other expansions the AI would play Council Room BM, so you'd be forced to not pick a strategy that's too slow to set up.
The most annoying thing the AI does is with Port: I'll settle on my engine, decide what pieces I need to focus on and what cards I need to get them, this card for trashing, etc, and leave the Ports until I need them. Oops, the Ports are gone already. It's not uncommon to watch the CPU play Port, play another Port, play 4 coppers, buy a Port and gain another. Next turn: play 3 or 4 ports and buy another Port. It's annoying because A) The AI's deck full of Ports is bad and offers no challenge B) I needed 4 Ports or so to make this engine work, and now there's none. So I still beat the opponents decks easily, but I didn't get my engine going 100% to do it. This is especially annoying in the 3 player games.