I finished Dawkin's The God Delusion and Harris' Letter to a Christian Nation in the past few weeks.
Its really interesting to finally see a contingient of humanity stand up against religion. That's interesting because its basically fighting for nothing. These atheists (although Harris is quick to point out that "atheist" is a silly word, read below) aren't trying to convert you per se, they're trying to tell you that your religion is pretty silly.
Both agree that we are ALL atheists when it comes to some religions. For example, most of us are atheists to Zeus nowadays (sorry dude). In fact, everyone is probably an athiest to hundreds of different religions. Just pure atheists go one religion further and actually believe in none. They go on with the idea that the word 'athiest' is rather silly in that we don't often categorized un-members of something (although I can think of a counter-example in the word "unemployed").
I absolutely loved Dawkin's earlier books The Blind Watchmaker and The Selfish Gene. The biggest fault of the God Delusion for me was that Dawkins tends to get angry at times. I understand that in his videos of talking to indignant religious people (youtube on "root of all evil"), but there doesnt seem to be much purpose for it in a book. It was an unwelcome distraction (reminded me of Aronson's The Social Animal where he kept being overly politically correct with facts like "men often have more muscle mass than women - Not to say women can't be strong!!! its just that..")
Letter to a Christian Nation is all of 80 pages and can be read in one bus ride (QED). Its clean and concise and worth it given the modest investment.
Both books bring up plenty of Bible contradictions (they both focused on only the Bible it seems) and meta-views of the universe (e.g. if one believes the universe is so complex as to have only been possibly created by a creator, then how was the yet-even-far-more-complex creator created?).
I don't expect either of these book to change many minds given that I doubt many people who are religious will read them. Of decent value is Dawkins discussion on the misconceptions of stem cell research and evolution. He says that many religious people tell him that the universe (or the eye, or the cardio-vascular system, or any other sufficiently complex system) could not have developed by accident. To which he points out as the biggest misunderstanding of evolution.
That evolution is never by accident. Its by massively parallel trial and error (Note that genetic algorithms in artificial intellgence work this way, a million computers (or simulated computers) try a million different slightly different attacks at a problem, the best approach is kept and forms the basis for the next million approaches. All losers are unmercifully deleted). That "part" of an eye is truly an advantage over your neighbor that has no eye at all. And that if your other neighbor has even a better part, his vision gives him an advantage over you. In other words, the eye did not evolve overnite. It began as something that could barely detect light and dark, and slowly got better and better as it evolved to provide more advantage to its owner.
Anyway, these books are just some more fun examples of world religions. Dawkins tells one story of describing an aboriginal religion that involved witches that fly in the night and shoot poison darts at bad people (i.e., "sinners"). To which a priest at his table laughed at what nonsense that religion was. To which Dawkins basically replied that the priest's religion didn't make much more sense itself (plenty of tense moments therein).
The overtones are of course that more people die and more wars are fought for religion than anything else. That God sure wants us to kill each other it seems. Both authors would be happier if religion simply didn't exist. Overall, there isn't any terribly unobvious stuff in there, but both are good reads.