The skill tree has a few issues making some of the upgrades detrimental in the short term without making that known to a player, this game isn't a puzzle and does not benefit from obscuring information.
Shadowstep in particular and unlocking the barbarian wouldn't be very useful given the team setup before them. I'm sure there is more balance choices, but none should stunt certain progression choices as those two. Sorry, I only really noticed it seriously on the Shadowstep one, losing a significant amount of income made the idea of purchasing the other vague upgrades seem a lot less interesting.
I can usually finish most of these games, but that was off-putting to say the least.