As other posters have said, it depends on you.
I really enjoy the ICU environment because of the challenges is presents. When you think about it, the ICU level is as high as it goes so if your patient goes bad, you're it. You have to deal with it and do your best because there isn't anywhere else for them to go unless it's heaven.:heartbeat
A good orientation, as others have said, is important. It will really help you develop your skills. We had 6 weeks of classroom lectures during our orientation plus working on the floor. It was quite intense!
What I think will really make or break you are the people you work with though. A good group of coworkers are worth more than their weight in gold! I can't count how many times I've asked everyone I work with questions that they have answered. If it weren't for them, this ship would have sailed moths ago.