Is it harder to use?

Well, maybe a little. It's not difficult, but it's a little more involved. You have to close the lid and engage the lock (the type of lock will be different, set the pressure control to one of usually three settings (no extra pressure, for steaming, low pressure, for veggies and that sort of thing, and high pressure, for stuff that takes longer.) You start the timer when the valve starts to hiss.... you've reached cook temperature, so that's when the time starts. When you're done cooking, you need to cool it again before opening; different recipes will call for different methods. (The fast way is just to run the cooker under cold water; it'll release in about twenty seconds.)

So, yeah, it's a little more involved; you can't just dump and forget, you have to pay a little attention. But you don't have to babysit; as long as a hiss and then a timer will break you out of whatever you're doing, you can generally put it on the heat and walk away, come back and set the timer when it hisses (and reduce the heat way down, to just enough to hold pressure), and then come back when the timer beeps. If you forget it completely, you can wreck it like any other pot, although it will take longer than with most (since the water has to all boil away before it will be ruined, and that's a very slow process when the escape valve is so small.)

I don't think there's any way to irretrievably damage a crockpot except by dropping and breaking it. But if you can avoid destroying regular pans, a pressure cooker should be safe.

You don't, by the way, have to get the times exactly right. There is SOME slop. But you can't just leave stuff for hours and hours. :)