OK, I've been playing this most of the day now (solo with one investigator - Roland).
Since I was learning, I used the recommended starter deck and chose Standard difficulty. The first scenario was an enjoyable learning experience and the deck was sufficient to the challenge. However, the other two scenarios were MUCH harder. I barely made it through the second one and gave up on the third after two failed attempts.
Whilst I think the game has a lot of potential, the starter deck (and possibly the current card pool) seems too weak (at least for solo play) - I often found I couldn't equip assets as that slot was already filled, ending up with a max hand of cards that I couldn't use without dumping an existing asset. With such a weak deck, the card draw was just too random.
Another problem I encountered was that it takes several turns to kill most enemies (more without +damage cards in play), during which time I wasn't gaining clues and the agenda was advancing. I think having more players would alleviate this.
A side effect to both of the above was drawing a weakness was utterly debilitating.