I have read the original seven book series a few times. The movie stayed true enough to the original, that looking for variances would be picking nits.
It did start a bit slowly, but I think they wanted to stress the isolation of the children, the mystery of the wardrobe, and the rivalry among the boys.
Certain events in LOTR moved me, but I found myself getting a bit choked up BEFORE a few things in Narnia happened. Maybe because it was children and not Hobbits.
I put it on LOTR level, but that is only my opinion.
BTW: Narnia did another $30M this weekend!!