I tried, and quickly binned, a bunch of Geronimo Stilton early readers a couple years ago. This comic book series is catching our son's attention. They're okay... not what I'd choose, not poor enough to reject. If you don't already read comics and know how to differentiate quality within the format then *please* do not begin here. :)
I guess the best I can say is there are many difficult words and my son is learning to read those by choice. The plots in this series bore me, but I'm not seven years old so my opinion on such matters should be viewed with some suspicion.
Borrow don't buy.