I'm playing a very recent SVN and I don't think Crime is unbalanced or too difficult. (Playing with Flexible difficulty and I've been on Immortal for a while). I do think it steepens the learning curve much more than any other C2C concept.
I think the main issue is how crime
indirectly affects everything else.
Unhappiness, Unhealthiness, and 'natural' city maintenance (Dist. from palace and No. of cities) have become almost negligible in C2C. Instead, the property system is the game mechanic that limits expansion. I like the crime system because it fills that role; without it I would just build bigger and bigger. As mentioned earlier, the properties are like another layer over BtS's Happiness and Health mechanic, which itself is like a layer over the food bar and general productivity. This creates an ease-of-access issue: all of the handy enhanced UI inherited from BUG shows information for health, happiness and gold. (As intended, I believe,) The effects of crime doesn't hit the city or the treasury until many turns after the sources of crime is introduced. I can roll-over a Bandit's Hideout, see the +5

and +10 crime, and think "I can handle that" or "that's worth it" because I won't know the full effect that +10 crime will really cause.
Someone commented earlier "might as well just pay a crime tax" and I think he hit the nail on the head. That's what crime really is, as a game mechanic: it limits growth. Nobody mentioned this yet in the thread, but one good solution to crime is to start using the "avoid growth" button. In vanilla BtS, all of these negative effects and necessities of managing a big city were bundled into and assumed as the city maintenance cost. Now that the police force is pulled out of the city onto the map, the cost is pulled out of the city maintenance and into the unit maintenance. But essentially, it is a city maintenance. This causes the same ease-of-access issue: until I've played several games, I don't know how big of a city is too big, or how many LE I need to send with my next settler.
All of this contributes to the learning curve: not only is it high due to all the new content, it's steep because the effects are all indirect. The connection isn't very visible. I very much like the crime system now. However, truth be told, Crime is THE limiting agent, at least in the Ancient Era. Crime determines how big an empire gets. Once you learn how it works it doesn't feel very restrictive, but I think new players may take a while to realize it, treating it as an extra feature on the side.
I don't mind the learning curve, but maybe this isn't what you've all intended.