I just read Da Vinci Code last week, and could hardly put it down--I finished it within two days, just reading on the subway to/from work and at home in the evening. Incredible book...best I've read in a while.
So, my answer is no, you shouldn't stop reading Da Vinci Code halfway through, because I don't think it's physically possible to do that.
But seriously, I can't really answer the original question yet, but I have already ordered Angels and Demons, so I should have an answer pretty soon!
Common sense is not so common. -Voltaire