Well, think about it this way: according to the article in GameInformer(the magazine, not the extra web content), Portal was a testbed. It was an experiment. It was stuffed into the HL universe because they didn't want to spend a lot of time creating a new universe for something that might not go so well. It had 8 people working on it. Basically, development was constricted. Now, enter Portal 2: 20 more people are on the team, including 2 more comedy gold writers, and Valve is giving them whatever they need. You think about how good it's going to be.