Having read the book prior to watching the movie, I felt that the movie cut out quite a bit of the details which were, for me, the most compelling parts of the story. The movie was unable to fully develop the characters and plot; any attempts to do so were also quite weak, which would explain the comments on the boring bits.
The movie also introduces some additional out-of-this-world elements
like the huge mole and giant bug, giving the movie a fairy tale/magical twist which I felt ruined the plot's "credibility".
However, I think the movie set and props were great and the visuals were commendable. Great job also by Saoirse as Lina and Harry as Doon.
This movie is worth a watch, just don't expect too much and enjoy being temporarily transported into the City of Ember. You can expect better from reading the book!