Well, if you're part of the "writers = unpaid; authors = paid" group, then I'll have to get back to you with an answer.
If you're part of "author = written a book doesn't matter if it sold yet" group, then I'd have to say the most surprising thing about it is ...
...two books is the "norm" for a Big House contract on a debut author.
There isn't a novel in my catalog that isn't part of a series. Most are five-book series; though, I do have two that are planned as trilogies. I probably shouldn't mention the lone "unlimited" series.
How am I supposed to become the next Richard Castle (hellllllo, last night's season premiere!) with just TWO BOOKS? How am I supposed to establish a loyal following with just TWO BOOKS? How am I supposed to rocket to the top of the Best Seller List with just TWO BOOKS?
How am I supposed to buy James his Lamborghini with just TWO BOOKS?
That was my first surprise. I'm braced for more...