This is now my favourite Christopher Nolan film. Though I've only seen this, the two Batman films, and Memento...
I don't think the rules were too much considering the nature of their job. If this technology existed, it would make sense for people to start getting "dream training", so they've made these rules to keep things as realistic as possible to avoid detection. But, it's been a few weeks since I've seen it, so maybe I'm forgetting something...
Oh, and it kinda pisses me off when people say they didn't get it because they're basically just saying they didn't pay attention.