I don't mind the occasional error, but some eBooks get ridiculous. One of the characters in a book I read was named $Acute;ibhear evereywhere in at least 2 books. Not sure how to pronounce that one.
And The Hobbit was horrible when it first came out. There were multiple errors on every page. (That was an iPod Touch sized page not a hardcover sized one.) Fortunately Fictionwise had a corrected version later.