I haven't used that book but I wanted to chime in on the easy reader stuff that we have liked. I am not sure where a child is at (reading level anyways) when they finish 100 easy lessons, but you mentiond looking for easy readers.
Danny and the Dinosaur by Syd Hoff
Morris the Moose books by Wiseman
Amelia Bedelia books by Parish
Diary of a worm (spider and fly too) by Cronin
Fly Guy (series) by Tedd Arnold
The Cat in the Hat by Seuss
Green Eggs and Ham by Seuss
Also, there are some non-fiction too that are "I can read books". Here is one called "First Flight" http://www.amazon.com/First-Flight-S...4563257&sr=1-3
Scroll down and look at the "Customers who bought this item also bought" section to find more.
Then, we also like the readers put out by AAS. There are multiple stories in each volume. They are hardcover and bound nicely. They are nice stories with lots of specific practice. Meaning, lots of times the "easy readers" will have several words that aren't decodable. My dd needs words that are decodable right now.
We also use the I See Sam readers. These go up to fourth grade level, so you would just choose the group that works for you child. This is a link to purchase them--but all levels are present and you can view samples of each level. http://www.3rsplus.com/
I have seen level 1 free online, but I would guess that you should click on the one that is bright blue and says Lids and Logs as the first title.
Then, for early chapter books there are the Junie B Jones & Magic Tree House of course. They are all around a grade 2 level. But, we really like the Mercy Watson books. They are a simlar level and we find them adorable. http://www.amazon.com/Mercy-Watson-S...4563115&sr=1-1
Well, I hope this gets you going in the right direction. For most kids, fluency comes with practice. Rereading favorites is also really good for fluency.