This guy is one of the worst writers to ever sell a book. I will preface my comments by saying that I'm Catholic but not overly religious. I believe in the tenets of Catholicism but I am a strong critic of the Church.
I read Angels and Demons first and thought that it was very poorly writen - more like a movie script than a novel. Then I tried to read DaVinci Code and couldn't finish it. The guy uses every cliche in the book, cannot write dialogue to save his life, the premise is unbelievable and the character development is non-existent (he might as well just say: "picture Indiana Jones without a whip"). My guess is that it only became a bestseller because it knocked the Church. I cannot express how bad a writer he is, I've read better stuff in the National Inquirer.
I don't mean to be too critical but I really didn't like his work and I read damned near everything.
That being said Angels and Demons is slightly better, in the same way that Police Academy 4 can be said to be better than Booty Call.
If you enjoyed HGG I suggest that you move on to Dirk Gently's Holistic Detective Agency. Hilarious work by the same author.
Moving away from straight fiction I urge you to read Bill Bryson. He is an American who has written for years about his travels and about the trials of an American living and raising a family in Britain. I recommend The Lost Continent, Neithre Here Nor There and Notes From a Small Island.