although I agree with all the comments about this development picture being normal (decoding first, higher comprehension levels later), I would suggest :
comic or manga type books, where there are pictures to go along with the words can be great for supporting comprehension, and upping the 'FUN!' quotient, especially if younger children's picture books are of less interest to your ds.
Vocab might not be 'super high' in these books, but story and entertainment can be pretty solid, and help to foster a true love of reading.
http://www.wired.com/geekmom/2012/03/geekmom-comic-book-corner-comic-books-for-kids/
